Add tests for rosdep checks

[cottsay]

These are the tests for the previously added rosdep checks. I found that in order to get good coverage, I needed to handle these cases:

1. Check a violation while other non-violating changes are also checked to ensure that none of the check optimizations bypass something that should have been checked
2. Check a violation while there are other possibly related violations to ensure that unexpected YAML structure doesn't break a different check

To exhaustively accomplish this, I made:

1. A set of "existing" rules that represent the "current" state of the rosdep DB
2. A set of "control" rules which should pass validation and are being checked
3. A set of rules which violate each check in one way or another.

A test is then performed for each violation alone, each violation with the set of "control" changes, and also every possible combination of 2 violations.

Note that we still don't have support for all of the violations we want in this checker, this PR is just to "catch up" on the missing tests.

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 78.45%. Comparing base (7b81baf) to head (5e33148).

Additional details and impacted files

@@             Coverage Diff             @@
##             main      #10       +/-   ##
===========================================
+ Coverage   44.57%   78.45%   +33.87%     
===========================================
  Files          13       13               
  Lines         673      673               
  Branches      176      176               
===========================================
+ Hits          300      528      +228     
+ Misses        367      128      -239     
- Partials        6       17       +11     

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[cottsay]

CI failure should be addressed by #11. Converting to draft until that is merged...

FIXED

[cottsay]

Back to draft until #14 is merged.

[cottsay]

Ugh, back to draft until #18 is merged.

No more "I'll add the tests in a later PR" business. This is ridiculous.