Add test ensuring identical translation keys share fallback names

[TheJulianJES]

Proposed change

This PR adds a test ensuring that if multiple entity metadata entries share the same translation key (e.g. child_lock), that their fallback names also all match (e.g. "Child lock").

So, one quirk can't have "Children lock" and the other "Child lock" as a fallback name if they share the same translation key of child_lock.

Additional information

This is needed as Home Assistant has a strings.json file that maps translation keys to friendly names.
This file is updated when bumping ZHA in HA. New translation keys are added by a script and their friendly name will, by default, be their fallback name.
If there were multiple different values per translation key, it would be somewhat "random" which value/name ends up in the strings.json file.

We just enforce what HA requires: no more than one friendly name per translation key. Currently, everything already passes.

(cc @prairiesnpr)

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 89.86%. Comparing base (57bcec8) to head (80bc6c3).

Additional details and impacted files

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##              dev    #3702   +/-   ##
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  Coverage   89.86%   89.86%           
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  Files         322      322           
  Lines       10387    10387           
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  Hits         9334     9334           
  Misses       1053     1053           

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