Feature Request: matrix project integration resrouce

Hello there.

I'd like to request a gitlab_project_integration_matrix resource to manage said integration (Project -> Settings -> Integrtations -> Matrix).

There are already similar existing resources:

• gitlab_project_integration_github
• gitlab_project_integration_jenkins
• gitlab_project_integration_jira
• gitlab_project_integration_telegram
• et al

This would be great for organizations that rely on Matrix for communications. Being able to push all messages for issues/pipelines/etc. is great, but when the configuration is spread across different repos the configuration becomes harder to maintain. That's the problem that terraform would solve, but unfortunately, there's no integration for that particular resource so we need to do it by hand.