add BinaryApp app type

[gilesknap]

Adds a new type of app which downloads a standalone binary, checks its hash and places it in the entrypoints folder.

Also adds the argocd module to demo_configuration in order to demonstrate the feature.

[codecov]

Codecov Report

Attention: Patch coverage is 87.93103% with 7 lines in your changes missing coverage. Please review.

Project coverage is 75.63%. Comparing base (32ef01f) to head (464f20f).
Report is 39 commits behind head on main.

Files with missing lines	Patch %	Lines
src/deploy_tools/app_builder.py	77.41%	7 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##             main      #26       +/-   ##
===========================================
+ Coverage   42.55%   75.63%   +33.07%     
===========================================
  Files          23       24        +1     
  Lines         860      911       +51     
===========================================
+ Hits          366      689      +323     
+ Misses        494      222      -272     

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[gilesknap]

@MJGaughran you may have noticed that I got all twisted up trying to rebase and merge these 3 PRs. Please just look away!