Support unsubscribing from a topic

[nkoenig]

🎉 New feature

Summary

Support websocket topic unsubscribe.

Test it

Test using: https://gitlab.com/ignitionrobotics/web/app/-/tree/topic_unsubscribe

Checklist

• Signed all commits for DCO
• Added tests
• Added example and/or tutorial
• Updated documentation (as needed)
• Updated migration guide (as needed)
• codecheck passed (See contributing)
• All tests passed (See test coverage)
• While waiting for a review on your PR, please help review another open pull request to support the maintainers

Note to maintainers: Remember to use Squash-Merge

[codecov]

Codecov Report

Merging #107 (5a4209d) into ign-launch3 (9201695) will not change coverage.
The diff coverage is n/a.

❗ Current head 5a4209d differs from pull request most recent head 73e8943. Consider uploading reports for the commit 73e8943 to get more accurate results

@@             Coverage Diff              @@
##           ign-launch3     #107   +/-   ##
============================================
  Coverage        30.24%   30.24%           
============================================
  Files                3        3           
  Lines              734      734           
============================================
  Hits               222      222           
  Misses             512      512           

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[german-e-mas]

Currently testing this on the client. Thanks for updating it with ign-launch3, I was missing the topic_types message.

[german-e-mas]

LGTM!