Refactor to extract Lockable

[fzyzcjy]

Changes

Please list issues fixed by this PR here, using format "Fixes #the-issue-number".

Checklist

• An issue to be fixed by this PR is listed above.
• New tests are added to ensure new features are working. Please refer to this page to see how to add a test.
• ./frb_internal precommit --mode slow (or fast) is run (it internal runs code generator, does auto formatting, etc).
• If this PR adds/changes features, documentations (in the ./website folder) are updated.
• CI is passing. Please refer to this page to see how to solve a failed CI.

Remark for PR creator

• ./frb_internal --help shows utilities for development.
• If fzyzcjy does not reply for a few days, maybe he just did not see it, so please ping him.

[codecov]

Codecov Report

Attention: Patch coverage is 98.97959% with 1 line in your changes missing coverage. Please review.

Project coverage is 94.27%. Comparing base (1dcc30b) to head (8770b57).

Files	Patch %	Lines
...wire/rust/spec_generator/misc/function/lockable.rs	96.87%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #2051      +/-   ##
==========================================
- Coverage   95.26%   94.27%   -0.99%     
==========================================
  Files         458      462       +4     
  Lines       16899    16894       -5     
==========================================
- Hits        16098    15927     -171     
- Misses        801      967     +166     

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