feat: configure github server url

[ferrarimarco]

Proposed changes

Allow the configuration of the GitHub server URL, and add some validation rules that check for common misconfigurations.

Close #5572

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[megamorf]

I had a look at the changes - the logic looks solid and the implementation is clean. Good job!

I'll take it for a test drive in our GHES instance today.

Edit:

Tested it like this:

jobs:
  lint:
    runs-on: [contoso-runners]
    steps:
      - name: Checkout Code
        uses: actions/checkout@v4
        with:
          # super-linter needs the full git history to get the
          # list of files that changed across commits
          fetch-depth: 0

      - name: Super-Linter
        uses: super-linter/super-linter/slim@fix-github-domain
        env:
          GITHUB_CUSTOM_API_URL: ${{ github.api_url }}
          GITHUB_CUSTOM_SERVER_URL: ${{ github.server_url }}
          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
          # [... configuration options omitted ...]

It appears to be working correctly. Some behaviours of the linters seems to have changed as v5 was not reporting findings while v6 does but IMO that's unrelated to the GHES compatibility issue and your fix.

We cannot use GITHUB_DOMAIN as the github context does not offer a variable with just the hostname of the instance.

[ferrarimarco]

Thanks for the feedback @megamorf !