Support for macOS static framework

Any plans for this?

I'm guessing it would look pretty similar to other static framework implementations, I could take a stab at a PR.

No file, test, or entry point is named in the issue. Compare the existing static framework implementations in rules_apple, then identify the relevant macOS rule entry point and expected validation coverage. Done means the repository supports building a macOS static framework with documented behavior and passing validation.

Written by the indexing model from the issue text.