[snap] GUI-less snap Launchpad integration

[sharder996]

This PR makes the following changes in order to automate the building of a gui-less Multipass snap in Launchpad for the s390x and ppc64 architectures:

1. Additional supported architectures added to snap/snapcraft.yaml. They have been added here in order to minimum the number of edits made to the gui-less snapcraft file.
2. Mirrored version of snap/snapcraft.yaml without GUI located at packaging/gui-less/snap/snapcraft.yaml. Because pathing implications and assumptions made by snapcraft, the source of some parts are now the GitHub remote instead of your local development clone.
3. Python script to programmatically generate the mirrored snapcraft file. This is where edits to the gui-less snapcraft build should be defined.
4. CI step added to the Lint workflow which verifies that any edits made to the original snapcraft file are properly manifested in the gui-less version.
5. Optional pre-commit hook that regenerates the mirrored snapcraft file if snap/snapcraft.yaml has been edited.

The Launchpad side can be observed here. Once this is merged in, the snapcraft recipe in Launchpad will be modified to track the main branch, and additional recipes added to mirror the candidate and beta recipes, except without the GUI and on the s390x/ppc64 architectures.

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MULTI-2379

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 87.45%. Comparing base (c702588) to head (4491870).
⚠️ Report is 65 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #4822      +/-   ##
==========================================
- Coverage   87.54%   87.45%   -0.09%     
==========================================
  Files         258      258              
  Lines       14155    14094      -61     
==========================================
- Hits        12391    12324      -67     
- Misses       1764     1770       +6     

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[xmkg]

Alright, this is as good as it gets. Thanks, @sharder996!