chore: Enforce coding styles on build

[benjiro]

This PR

A follow on from the previous PR that removed unused using, this will make sure it won't occur in the future. https://github.com/open-feature/dotnet-sdk/pull/240#issuecomment-1956892758

• Enforce code styles on build
• Error on unused usings
• Apply workaround for IDE0005 rule

Related Issues

Fixes https://github.com/open-feature/dotnet-sdk/pull/240#issuecomment-1956892758

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 94.47%. Comparing base (fa25ece) to head (9db9ec0).

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #242 +/- ## ======================================= Coverage 94.47% 94.47% ======================================= Files 27 27 Lines 1104 1104 Branches 119 119 ======================================= Hits 1043 1043 Misses 37 37 Partials 24 24 ```

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