Fix broken URLs for old GitLab instances

[k-yle]

Closes #2162

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Description

Since #2022, anyone using an old installation of GitLab can no longer use the View on Remote feature; all URLs produce a 404 since gitlab changed the URL format, and GitLens only supports the new format as of #2022

This PR adds a new option to the gitlens.remote setting, called version. For example:

  "gitlens.remotes": [{ "domain": "example.intranet.net", "type": "GitLab", "version": "17" }],

This field could be reused by other providers in the future, if they need version-specific logic.

For gitlab, if the version is too old, the URLs will not include the /-/ infix

Checklist

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