docs: update docstrings to adhere to Google docstrings standard

[DonDebonair]

• update docstrings for Message
• update docstrings for Command
• update docstrings for BlockAction
• update docstrings for ModalSubmission and ModalClosure
• update docstrings for decorators
• update docstrings for storage classes

[codecov]

Codecov Report

Attention: Patch coverage is 75.00000% with 3 lines in your changes missing coverage. Please review.

Project coverage is 79.71%. Comparing base (fdfaaf0) to head (35bf837).
Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
src/machine/plugins/message.py	66.66%	2 Missing ⚠️
src/machine/plugins/base.py	83.33%	1 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #1225   +/-   ##
=======================================
  Coverage   79.71%   79.71%           
=======================================
  Files          36       36           
  Lines        1957     1957           
=======================================
  Hits         1560     1560           
  Misses        397      397           

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