Lint: add a rule for order import sorting (#818)

@remedcu
[mentioned](#731 (comment))
that `solhint` now has a rule to sort imports in contracts and we can
implement #731

This PR:
- Enables `imports-order` solhint rule and fixes imports across
contracts

---------

Co-authored-by: Shebin John <admin@remedcu.com>

Author: mmv08

.solhint.json

@@ -13,6 +13,7 @@
         "reason-string": "off",
         "no-empty-blocks": "off",
         "avoid-low-level-calls": "off",
-        "gas-custom-errors": "off"
+        "gas-custom-errors": "off",
+        "imports-order": "warn"
     }
 }

contracts/Safe.sol

@@ -1,19 +1,19 @@
 // SPDX-License-Identifier: LGPL-3.0-only
 pragma solidity >=0.7.0 <0.9.0;
 
+import {FallbackManager} from "./base/FallbackManager.sol";
 import {ITransactionGuard, GuardManager} from "./base/GuardManager.sol";
 import {ModuleManager} from "./base/ModuleManager.sol";
 import {OwnerManager} from "./base/OwnerManager.sol";
-import {FallbackManager} from "./base/FallbackManager.sol";
 import {NativeCurrencyPaymentFallback} from "./common/NativeCurrencyPaymentFallback.sol";
-import {Singleton} from "./common/Singleton.sol";
-import {SignatureDecoder} from "./common/SignatureDecoder.sol";
 import {SecuredTokenTransfer} from "./common/SecuredTokenTransfer.sol";
+import {SignatureDecoder} from "./common/SignatureDecoder.sol";
+import {Singleton} from "./common/Singleton.sol";
 import {StorageAccessible} from "./common/StorageAccessible.sol";
-import {Enum} from "./libraries/Enum.sol";
-import {ISignatureValidator, ISignatureValidatorConstants} from "./interfaces/ISignatureValidator.sol";
 import {SafeMath} from "./external/SafeMath.sol";
 import {ISafe} from "./interfaces/ISafe.sol";
+import {ISignatureValidator, ISignatureValidatorConstants} from "./interfaces/ISignatureValidator.sol";
+import {Enum} from "./libraries/Enum.sol";
 
 /**
  * @title Safe - A multisignature wallet with support for confirmations using signed messages based on EIP-712.

contracts/SafeL2.sol

@@ -1,12 +1,10 @@
 // SPDX-License-Identifier: LGPL-3.0-only
 pragma solidity >=0.7.0 <0.9.0;
 
-import {Safe, Enum} from "./Safe.sol";
-
-// Imports are required for NatSpec validation of the compiler, and falsely detected as unused by
-// the linter, so disable the `no-unused-imports` rule for the next line.
+// The import is used in the @inheritdoc, false positive
 // solhint-disable-next-line no-unused-import
 import {ModuleManager} from "./base/ModuleManager.sol";
+import {Safe, Enum} from "./Safe.sol";
 
 /**
  * @title SafeL2 - An implementation of the Safe contract that emits additional events on transaction executions.

contracts/base/GuardManager.sol

@@ -2,10 +2,10 @@
 /* solhint-disable one-contract-per-file */
 pragma solidity >=0.7.0 <0.9.0;
 
-import {Enum} from "../libraries/Enum.sol";
-import {SelfAuthorized} from "../common/SelfAuthorized.sol";
-import {IERC165} from "../interfaces/IERC165.sol";
-import {IGuardManager} from "../interfaces/IGuardManager.sol";
+import {SelfAuthorized} from "./../common/SelfAuthorized.sol";
+import {IERC165} from "./../interfaces/IERC165.sol";
+import {IGuardManager} from "./../interfaces/IGuardManager.sol";
+import {Enum} from "./../libraries/Enum.sol";
 
 /**
  * @title ITransactionGuard Interface

contracts/base/ModuleManager.sol

@@ -1,11 +1,11 @@
 // SPDX-License-Identifier: LGPL-3.0-only
 /* solhint-disable one-contract-per-file */
 pragma solidity >=0.7.0 <0.9.0;
-import {Enum} from "../libraries/Enum.sol";
-import {SelfAuthorized} from "../common/SelfAuthorized.sol";
+import {SelfAuthorized} from "./../common/SelfAuthorized.sol";
+import {IERC165} from "./../interfaces/IERC165.sol";
+import {IModuleManager} from "./../interfaces/IModuleManager.sol";
+import {Enum} from "./../libraries/Enum.sol";
 import {Executor} from "./Executor.sol";
-import {IModuleManager} from "../interfaces/IModuleManager.sol";
-import {IERC165} from "../interfaces/IERC165.sol";
 
 /**
  * @title IModuleGuard Interface

contracts/examples/guards/BaseGuard.sol

@@ -1,8 +1,8 @@
 // SPDX-License-Identifier: LGPL-3.0-only
 pragma solidity >=0.7.0 <0.9.0;
-import {IERC165} from "../../interfaces/IERC165.sol";
-import {BaseTransactionGuard, ITransactionGuard} from "../../base/GuardManager.sol";
-import {BaseModuleGuard, IModuleGuard} from "../../base/ModuleManager.sol";
+import {BaseTransactionGuard, ITransactionGuard} from "./../../base/GuardManager.sol";
+import {BaseModuleGuard, IModuleGuard} from "./../../base/ModuleManager.sol";
+import {IERC165} from "./../../interfaces/IERC165.sol";
 
 /**
  * @title BaseGuard - Inherits BaseTransactionGuard and BaseModuleGuard.

contracts/examples/guards/DebugTransactionGuard.sol

@@ -1,8 +1,8 @@
 // SPDX-License-Identifier: LGPL-3.0-only
 pragma solidity >=0.7.0 <0.9.0;
 
-import {Enum} from "../../libraries/Enum.sol";
-import {ISafe} from "../../interfaces/ISafe.sol";
+import {ISafe} from "./../../interfaces/ISafe.sol";
+import {Enum} from "./../../libraries/Enum.sol";
 import {BaseGuard} from "./BaseGuard.sol";
 /**
  * @title Debug Transaction Guard - Emits transaction events with extended information.

contracts/examples/guards/OnlyOwnersGuard.sol

@@ -2,9 +2,9 @@
 /* solhint-disable one-contract-per-file */
 pragma solidity >=0.7.0 <0.9.0;
 
-import {Enum} from "../../libraries/Enum.sol";
-import {BaseTransactionGuard} from "../../base/GuardManager.sol";
-import {ISafe} from "../../interfaces/ISafe.sol";
+import {BaseTransactionGuard} from "./../../base/GuardManager.sol";
+import {ISafe} from "./../../interfaces/ISafe.sol";
+import {Enum} from "./../../libraries/Enum.sol";
 
 /**
  * @title OnlyOwnersGuard - Only allows owners to execute transactions.

contracts/handler/CompatibilityFallbackHandler.sol

@@ -1,10 +1,10 @@
 // SPDX-License-Identifier: LGPL-3.0-only
 pragma solidity >=0.7.0 <0.9.0;
 
-import {TokenCallbackHandler} from "./TokenCallbackHandler.sol";
-import {ISignatureValidator} from "../interfaces/ISignatureValidator.sol";
-import {ISafe} from "../interfaces/ISafe.sol";
+import {ISafe} from "./../interfaces/ISafe.sol";
+import {ISignatureValidator} from "./../interfaces/ISignatureValidator.sol";
 import {HandlerContext} from "./HandlerContext.sol";
+import {TokenCallbackHandler} from "./TokenCallbackHandler.sol";
 
 /**
  * @title Compatibility Fallback Handler - Provides compatibility between pre 1.3.0 and 1.3.0+ Safe Smart Account contracts.

contracts/interfaces/ISafe.sol

@@ -1,11 +1,11 @@
 // SPDX-License-Identifier: LGPL-3.0-only
 pragma solidity >=0.7.0 <0.9.0;
 
-import {Enum} from "../libraries/Enum.sol";
-import {IModuleManager} from "./IModuleManager.sol";
-import {IOwnerManager} from "./IOwnerManager.sol";
+import {Enum} from "./../libraries/Enum.sol";
 import {IFallbackManager} from "./IFallbackManager.sol";
 import {IGuardManager} from "./IGuardManager.sol";
+import {IModuleManager} from "./IModuleManager.sol";
+import {IOwnerManager} from "./IOwnerManager.sol";
 
 /**
  * @title ISafe - A multisignature wallet interface with support for confirmations using signed messages based on EIP-712.