Support Swift CXX Interop

[waahm7]

Issue #, if available: https://github.com/awslabs/aws-crt-swift/issues/166

Description of changes:

• Don't include inl files as part of extern C. We use AWS_EXTERN_C_BEGIN and AWS_EXTERN_C_END within the inl files.
• Ideally, we should add CI in common as well, but I don't know how. I will add CI in crt-swift.

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

[codecov-commenter]

Codecov Report

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

Project coverage is 83.84%. Comparing base (f58e807) to head (220324f).

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #1160 +/- ## ======================================= Coverage 83.84% 83.84% ======================================= Files 57 57 Lines 5992 5992 ======================================= Hits 5024 5024 Misses 968 968 ```

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