cmake: uppercase all the OPENSSL variables

[dkropachev]

Summary

Rename OpenSSL-related CMake variables and module file to follow the uppercase OPENSSL_* naming convention used throughout the build system.

Context

All OpenSSL-related CMake variables in the project use the uppercase OPENSSL_* convention (e.g., OPENSSL_VERSION, OPENSSL_INCLUDE_DIR, OPENSSL_LIBRARIES, CASS_USE_OPENSSL). However, a few places used inconsistent casing:

• The openssl_name helper variable used lowercase
• The FindOpenSSL.cmake module file and its find_package(OpenSSL) call used mixed-case

Incorporates changes from PR #434 by @MaikeR-TV (file rename + find_package update), with additional fixes for find_package_handle_standard_args consistency.

Changes

• Renamed openssl_name variable to OPENSSL_NAME in cmake/Dependencies.cmake and cmake/FindOPENSSL.cmake
• Renamed cmake/FindOpenSSL.cmake to cmake/FindOPENSSL.cmake (from PR fix spelling for OpenSSL in cmake #434)
• Changed find_package(OpenSSL) to find_package(OPENSSL) in cmake/Dependencies.cmake (from PR fix spelling for OpenSSL in cmake #434)
• Updated all three find_package_handle_standard_args(OpenSSL ...) calls to find_package_handle_standard_args(OPENSSL ...) so CMake correctly sets OPENSSL_FOUND

No behavioral changes — all modifications are naming consistency fixes.

Testing

# Configure
cmake -S . -B build -DCMAKE_BUILD_TYPE=Release

# Full lint gate
make check

Both pass successfully.

Links

• Incorporates: fix spelling for OpenSSL in cmake #434
• Related macOS CI issue (pre-existing, unrelated): CI: macOS packages build fails — Rust toolchain missing from macos-15-intel runner #436

[dkropachev]

@Lorak-mmk , @wprzytula , macOS issue fixed here - #437