Lock Improvements for [SR-12851]

[tgymnich]

This PR contains the following improvements to locks needed for SR-12851.

1. Added ReadWriteLock. (Using GCD instead for windows compatiblity)
2. Added property wrapper @ThreadLocal to address an issue where FileLock could be used in way that would unlock/lock the lock from another thread without the user realizing. --> Making FileLock thread safe
3. Enabled FileLock to obtain an exclusive or a shared lock.

[compnerd]

Please do not merge this without testing on Windows, it will break the s-p-m build. pthread_* functions are definitely not going to work on Windows.

[tgymnich]

I am trying to figure the windows thing out right know. I can replace the pthread stuff with GCD.

[tgymnich]

The tests I've added for FileLock don't seem to run under Windows even before my changes. I keep getting TSCBasic.FileSystemError.unknownOSError(32).
Update: Fixed by changingdwShareMode in CreateFileW call.

[tgymnich]

The property wrapper @AutoClosing still feels a bit hacky. I am open for suggestions on wrapping a file descriptor and closing it on deinit. This is needed for the thread local storage to properly close the file descriptor.

Alternatives considered:

1. Don't use a property wrapper, use a "normal" wrapper instead e.g. FileDescriptor
2. Don't make FileLock thread safe. Just add a comment, that it's not thread safe.
3. Use locks.

[neonichu]

@swift-ci please test

[neonichu]

@compnerd Do we have any separate Windows CI for TSC right now?

[neonichu]

@swift-ci please smoke test

[shahmishal]

The Swift project moved the default branch to main and deleted master branch, so GitHub automatically closed the PR. Please re-create pull request with main branch.

More detail about the branch update - https://forums.swift.org/t/updating-branch-names/40412