[FIX (CI)] Adjustments to Sample Build actions

[NotHyper-474]

This PR does a couple of adjustments to the Samples Build Action workflow:

• The haxelib cache now uses the hash sum of all hmm.json files present in the samples. This helps avoid having duplicate cache entries.
  • This required adding a .gitattribute file to enforce the same line ending across targets, ensuring that the hashes don't differ between them.
  • This is temporary until I find out why the generated hmm file itself is different on Windows but not on Linux and macOS
• It now won't update haxelib itself, because that just added unnecessary time.
• A build action will now be cancelled once another one starts.