Add functions for identifying changes to YAML files

[cottsay]

No description provided.

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 0% with 62 lines in your changes missing coverage. Please review.

Project coverage is 62.79%. Comparing base (e6f3e7a) to head (6af1152).

Files	Patch %	Lines
rosdistro_reviewer/yaml_changes.py	0.00%	62 Missing ⚠️

❗ There is a different number of reports uploaded between BASE (e6f3e7a) and HEAD (6af1152). Click for more details.

HEAD has 5 uploads less than BASE

Flag	BASE (e6f3e7a)	HEAD (6af1152)
	16	11

Additional details and impacted files

@@             Coverage Diff             @@
##             main       #4       +/-   ##
===========================================
- Coverage   98.18%   62.79%   -35.40%     
===========================================
  Files           3        4        +1     
  Lines         110      172       +62     
  Branches       28       50       +22     
===========================================
  Hits          108      108               
- Misses          0       62       +62     
  Partials        2        2               

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[nuclearsandwich]

There was one general purpose function that I stumbled on out of context but nothing blocking.