Teach the tabs engine about the ability to close inactive tabs.

[mhammond]

This also includes #6281 - you might prefer to review both together or review that by itself, then review this (ie, just the tabs engine changes) once that is merged.

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• Breaking changes: This PR follows our breaking change policy
  • [ ] This PR follows the breaking change policy:
    • This PR has no breaking API changes, or
    • There are corresponding PRs for our consumer applications that resolve the breaking changes and have been approved
• [ ] Quality: This PR builds and tests run cleanly
  • Note:
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• [ ] Tests: This PR includes thorough tests or an explanation of why it does not
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  • Any new dependencies are accompanied by a summary of the due diligence applied in selecting them.

Branch builds: add [firefox-android: branch-name] to the PR title.

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 0% with 149 lines in your changes missing coverage. Please review.

Project coverage is 22.54%. Comparing base (608b930) to head (1b8b190).

Files	Patch %	Lines
components/tabs/src/storage.rs	0.00%	53 Missing :warning:
...fxa-client/src/internal/close_all_inactive_tabs.rs	0.00%	52 Missing :warning:
components/fxa-client/src/internal/device.rs	0.00%	11 Missing :warning:
...t/src/internal/commands/close_all_inactive_tabs.rs	0.00%	10 Missing :warning:
components/fxa-client/src/internal/telemetry.rs	0.00%	10 Missing :warning:
components/tabs/src/schema.rs	0.00%	6 Missing :warning:
components/fxa-client/src/internal/commands/mod.rs	0.00%	4 Missing :warning:
components/fxa-client/src/push.rs	0.00%	3 Missing :warning:

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #6289      +/-   ##
==========================================
- Coverage   22.66%   22.54%   -0.12%     
==========================================
  Files         333      329       -4     
  Lines       29860    29974     +114     
==========================================
- Hits         6768     6759       -9     
- Misses      23092    23215     +123     

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[mhammond]

I think I got most of the review comments, but still a little unclear on how to proceed re the schema