Support GitLab

[hamelsmu]

For both self-hosted/enterprise and hosted

[hamelsmu]

Test GitLab.com

1. Create a new project on GitLab.com

2. Create a repo nbdev_test_gitlab (renamed it from nbdev_test, and manually creat a README

3. Ran nbdev_new, note that the automated setup doesn't work here, but it also does not break. It just prompts you to input some information. It does warn you that

Could not update the description & URL on the repo: hamelsmu/nbdev_test using $GITHUB_TOKEN.
Use a token with the correction permissions or perform these steps manually.

✏️ Action Item 1, we could probably skip these warning if we detect a Gitlab Target
✏️ Action Item 2, we could ignore the .github/ directory if we detect a Gitlab Target

... TODO

[jph00]

Forum thread with more details:
https://forums.fast.ai/t/example-nbdev-on-gitlab/98890