Feature/mutex abstraction

[matt001k]

What changed?

Add BM OS abstraction for mutex creation.
Utilzes bm_semaphore_create for binary semaphores.
Renames instances of bm_semaphore_create to bm_mutex_create due to the fact they are actually being used as mutexes.

How does it make Bristlemouth better?

Create mutex under more direct API call to increase clarity when invoking the API.

Where should reviewers focus?

All files are important. Good to validate that all API in bm_core have been renamed properly.

Checklist

• Add or update unit tests for changed code
• Ensure all submodules up to date. If this PR relies on changes in submodules, merge those PRs first, then point this PR at/after the merge commit
• Ensure code is formatted correctly with clang-format. If there are large formatting changes, they should happen in a separate whitespace-only commit on this PR after all approvals.

[victorsowa12]

👍