Add setting for custom Gitlab base URL

[vmoeykens]

Check for existing issues

• Completed

Describe the feature

Zed will automatically detect if the Git remote is a github.com or gitlab.com base URL and link commits to their appropriate location on the web. However, if the git repo remote is a custom Gitlab url such as gitlab.mycompany.com there is no way to utilize this feature. In theory as long as you specify it still follows Gitlab url conventions you could override the automatic detection and force it to use the base url of gitlab.mycompany.com and all the other url generation logic could stay the same.

If applicable, add mockups / screenshots to help present your vision of the feature

No response