Add battery_state_broadcaster (backport #2086)

[mergify]

This moves https://github.com/ipa320/ros_battery_monitoring/tree/main/battery_state_broadcaster to our repository.

For discsussion about this, see #1888 and especially #1888 (comment)

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This is an automatic backport of pull request #2086 done by Mergify.

[mergify]

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[codecov]

Codecov Report

❌ Patch coverage is 84.67532% with 59 lines in your changes missing coverage. Please review.
✅ Project coverage is 86.88%. Comparing base (0c16808) to head (10dc0e0).

Files with missing lines	Patch %	Lines
...tate_broadcaster/src/battery_state_broadcaster.cpp	77.54%	29 Missing and 24 partials ⚠️
...roadcaster/test/test_battery_state_broadcaster.hpp	92.40%	1 Missing and 5 partials ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           kilted    #2522      +/-   ##
==========================================
- Coverage   86.93%   86.88%   -0.06%     
==========================================
  Files         157      161       +4     
  Lines       15746    16131     +385     
  Branches     1342     1385      +43     
==========================================
+ Hits        13689    14015     +326     
- Misses       1586     1616      +30     
- Partials      471      500      +29     

Flag	Coverage Δ
unittests	86.88% <84.67%> (-0.06%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files with missing lines	Coverage Δ
...roadcaster/test/test_battery_state_broadcaster.cpp	100.00% <100.00%> (ø)
...aster/test/test_load_battery_state_broadcaster.cpp	100.00% <100.00%> (ø)
...roadcaster/test/test_battery_state_broadcaster.hpp	92.40% <92.40%> (ø)
...tate_broadcaster/src/battery_state_broadcaster.cpp	77.54% <77.54%> (ø)

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