Description

This PR does a few things:

1. Renames cpp/src/aztec to cpp/src/barretenberg, which will align the installed headers to match the libbarretenberg library that will get installed by feat: Add installation targets for libbarretenberg, wasm & headers #185
2. Moves cpp/src/aztec/CMakeLists.txt to cpp/src/CMakeLists.txt which allows all header files to be prefixed with the barretenberg namespace. This ensures that header includes when building the project are the same as when installed.
3. Updates all the header includes to use that barretenberg/ prefix.
4. Updates all local includes to use double-quotes instead of angle brackets. Generally, angle-brackets should only be used for system libraries and double-quotes should be used for user-defined headers. This also surfaces a lot of unnecessary or incorrect includes via clangd but I didn't want to change any of those in this PR.
5. Lots of clang-format changes since I touched files and it updates the entire file whenever one is staged.

Checklist:

• I have reviewed my diff in github, line by line.
• Every change is related to the PR description.
• I have linked this pull request to the issue(s) that it resolves.
• There are no unexpected formatting changes, superfluous debug logs, or commented-out code.
• There are no circuit changes, OR specifications in /markdown/specs have been updated.
• There are no circuit changes, OR a cryptographer has been assigned for review.
• I've updated any terraform that needs updating (e.g. environment variables) for deployment.
• The branch has been rebased against the head of its merge target.
• I'm happy for the PR to be merged at the reviewer's next convenience.
• New functions, classes, etc. have been documented according to the doxygen comment format. Classes and structs must have @brief describing the intended functionality.
• If existing code has been modified, such documentation has been added or updated.