Code Quality: Merged all interop into Win32PInvoke

[0x5bfa]

Summary

Just moved. Nothing has been modified other than formatting or adding extra references to avoid ambiguity.

PR Checklist

• Were these changes approved in an issue or discussion with the project maintainers? In order to prevent extra work, feature requests and changes to the codebase must be approved before the pull request will be reviewed. This prevents extra work for the contributors and maintainers.
  Closes #issue
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• Did you remove any strings from the en-us resource file?
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  • Was this change approved?
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[0x5bfa]

This is the last time touching around interop classes.
Deleted all interop classes and merged into single class, so we now can gradually replace them with CsWin32 without conflict (there were some classes that have the same definition) in the single place.

It's a bit large but ready for review.

[gumbarros]

LGTM except for this

[gumbarros]

LGTM