Add the ability to queue/dequeue revalidations on servers

[ocket8888]

Closes #2856

This PR adds context menu options to the servers table in TPv2 that allow for quick and easy queuing/dequeuing revalidations on a group of one or more servers.

I also plugged a testing gap in the servers API service - Capability-related methods were untested.

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Which Traffic Control components are affected by this PR?

• Traffic Portal (experimental v2)

What is the best way to verify this PR?

Make sure the provided e2e and unit tests pass. Queue/Dequeue updates on some server(s).

PR submission checklist

• This PR has tests
• This PR doesn't need documentation
• This PR doesn't need a CHANGELOG.md entry
• This PR DOES NOT FIX A SERIOUS SECURITY VULNERABILITY

[codecov]

Codecov Report

❌ Patch coverage is 57.14286% with 15 lines in your changes missing coverage. Please review.
✅ Project coverage is 65.73%. Comparing base (0b802b5) to head (bf9d673).
⚠️ Report is 148 commits behind head on master.

Files with missing lines	Patch %	Lines
...affic-portal/src/app/api/testing/server.service.ts	0.00%	12 Missing ⚠️
...e/servers/servers-table/servers-table.component.ts	80.00%	3 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##             master    #7923      +/-   ##
============================================
+ Coverage     65.65%   65.73%   +0.07%     
  Complexity       98       98              
============================================
  Files           323      323              
  Lines         12840    12863      +23     
  Branches        970      975       +5     
============================================
+ Hits           8430     8455      +25     
+ Misses         4050     4048       -2     
  Partials        360      360              

Flag	Coverage Δ
traffic_portal_v2	∅ <57.14%> (∅)
unit_tests	∅ <57.14%> (∅)

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[ocket8888]

Depends on #7925