Allow commands to work with .yml extension

[branic]

This change allows the "Apply YAML to cluster" and "Delete YAML from clsuter" commands to accpet a file ending in .yml. Using a .yml extension name for YAML files is common and widely used so it makes sense to support both the .yaml and .yml naming.

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 25.00000% with 3 lines in your changes missing coverage. Please review.

Project coverage is 43.86%. Comparing base (da60441) to head (862c5d2).
Report is 425 commits behind head on main.

Files	Patch %	Lines
src/yamlFileCommands.ts	25.00%	3 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##             main    #4357       +/-   ##
===========================================
+ Coverage   32.37%   43.86%   +11.49%     
===========================================
  Files          85       95       +10     
  Lines        6505     7746     +1241     
  Branches     1349     1641      +292     
===========================================
+ Hits         2106     3398     +1292     
+ Misses       4399     4348       -51     

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[vrubezhny]

Looks good to me. Thanks!