GitLab integration

[tommoor]

After #6406 similar to #4427

[linear]

OLN-346 GitLab integration

[almereyda]

To note, there is a basic GitLab integration snippets from the hosted instance at gitlab.com, which was contributed with #6217, #6290 and 8b6a760

The use case for self-hosted snippets is documented in:

• Custom Gitlab snippet domain prefix support. #6427

with some recent activity in the linked

• add self-host Gitlab Snippets #6317

that leads us to

• https://github.com/IamTaoChen/outline/tree/gitlab_new

[thedarkside]

That is what we are waiting for!

I would like to outline our requirements for a good integration here.

Besides the ability to embed issues, epics and merge requests from a selfhosted gitlab instance it would be beneficial when the embeds update automatically showing the current status like if an issue is open or closed, when was the last change etc.

Because our instance is private only, outline would need an api key to fetch the information.

Is this kind of integration planned?