Regression: GitHub dependencies don't work anymore

Description

#3318 broke the GitHub dependencies feature. Namely, files aren't added as Compile elements to the project file anymore, but as Content elements. Paket 5.176.2 works fine, 5.176.3 has the bug.

Repro steps

Use a project with a GitHub file dependency.

Run paket install with this repro: github-dependencies.zip.

Expected behavior

Code files should be added as Compile elements to the project file, if the languages match, e. g. .fs and .fsproj.

Actual behavior

Paket adds code files as Content elements to the project:

<Content Include="..\paket-files\rspeele\TaskBuilder.fs\TaskBuilder.fs">
  <Paket>True</Paket>
  <Link>paket-files/TaskBuilder.fs</Link>
</Content>

This snippet is from an F# project, but the same applies to C# projects. I'm not even sure if GitHub file dependencies work with SDK-style C# projects, which would pretty much result in the same thing as #3269.

Known workarounds

Use Paket 5.176.2.

Start with the attached github-dependencies.zip repro and compare Paket 5.176.2 with 5.176.3, then inspect the change referenced in #3318. The fix is done when matching F# and C# code files from GitHub dependencies are emitted as Compile elements rather than Content, with regression coverage for the repro.