Add support for the Tuya TS0021 2-gang switch

[rbaron]

Fixes #2847, fixes #3007

Proposed change

This PR adds support for the Tuya TS0021 2-button switch. Here's an example listing for this device.

Additional information

The implementation was tested on Home Assistant core 2024.7.0.

Checklist

• The changes are tested and work correctly
• pre-commit checks pass / the code has been formatted using Black
• Tests have been added to verify that the new code works

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 88.25%. Comparing base (d87f445) to head (f40a688).

Additional details and impacted files

@@            Coverage Diff             @@
##              dev    #3247      +/-   ##
==========================================
+ Coverage   88.18%   88.25%   +0.06%     
==========================================
  Files         301      302       +1     
  Lines        9412     9430      +18     
==========================================
+ Hits         8300     8322      +22     
+ Misses       1112     1108       -4     

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[TheJulianJES]

Thanks for the PR! I think this looks very good!
Awesome that you added tests 😄

[rbaron]

Thanks for reviewing it @TheJulianJES!

[TheJulianJES]

Nice, this loos good IMO! Thanks!