Thread local refactor

[pedromfedricci]

This PR removes previous thread_local's Mutex and MutexGuard types. Thread local nodes now need to be explicitly declared via thread_local_node! macro, instead of the previous approach of transparently defining them. The problem with transparent thread local nodes design is that locking APIs are easy to use incorrectly and cause panics (for the safe APIs) and undefined behiavior (for the unchecked variants). The new design requires explicit definition of static thread local node keys, and locking APIs require taking references to those static node keys, which makes a lot easier for callers to track them on source code and evaluate if they are already referenced (borrowed) within a closure scope. Operating over thread local nodes for locking is now part of the raw::Mutex's API, instead of defining a separated type just for them. Thread local nodes are borrowed at runtime, and their borrows live up to the end o the closure scope operating over them. See thread_local_node! macro, LocalMutexNode type and ..._lock_with_local_... functions documentation for more information.

Breaking changes:

• Removed thread_local module.
• Removed thread_local's Mutex and MutexGuard and their aliases.

Added:

• New thread_local_node! macro.
• New LocalMutexNode type.
• New try_lock_with_local function for raw::Mutex.
• New lock_with_local function for raw::Mutex.
• New try_lock_with_local_unchecked function for raw::Mutex.
• New lock_with_local_unchecked function for raw::Mutex.

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 95.00000% with 1 lines in your changes are missing coverage. Please review.

Project coverage is 97.95%. Comparing base (ecea470) to head (e45840b).

Files	Patch %	Lines
src/thread_local.rs	94.44%	1 Missing ⚠️

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Additional details and impacted files

@@            Coverage Diff             @@
##             main      #11      +/-   ##
==========================================
+ Coverage   96.99%   97.95%   +0.96%     
==========================================
  Files           5        5              
  Lines         233      196      -37     
==========================================
- Hits          226      192      -34     
+ Misses          7        4       -3     

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