[FR] Dynamic GitLab project selection via API queries

The issue names no repository files, tests, or entry points; start by locating GitLab connection configuration and project synchronization handling, then review the linked GitLab project-list API documentation. Done means projectQuery results are synchronized alongside groups and projects, with pagination handled as needed and duplicate projects imported only once.

Description

Add support for configuring which GitLab projects are mirrored/synchronized by using GitLab API queries.

Introduce a new optional parameter called projectQuery, which allows users to dynamically select projects to mirror based on GitLab API endpoints.

Proposed Configuration

The projectQuery parameter would be an array of strings.
Each string represents a GitLab API URL path (including query parameters) that returns a list of projects.

Example:

{
  "connections": {
    "gitlab-connection": {
      "type": "gitlab",
      "groups": [
        "..."
      ],
      "projects": [
        "..."
      ],
      "projectQuery": [
        "groups/group1/projects?include_subgroups=true",
        "groups/group2/projects?include_subgroups=false",
        "groups/group3/projects?include_subgroups=true&archived=false",
        "search?scope=projects&search=flight",
        "projects?topic=devops"
      ]
    }
  }
}

Here are a few endpoints that return a list of projects:

• https://docs.gitlab.com/api/projects.html#list-all-projects
• https://docs.gitlab.com/api/groups.html#list-a-groups-projects
• https://docs.gitlab.com/api/search.html#scope-projects.

Expected Behavior

All projects returned by the specified API queries should be mirrored in Sourcebot.
If a project is matched by multiple query strings, it must be imported only once (deduplication).
This feature should complement existing groups and projects configuration options.

Motivation

This would make GitLab synchronization more flexible and scalable, especially for organizations with:

• Large numbers of projects
• Complex group and subgroup structures

It would also reduce configuration maintenance by relying on GitLab’s API filtering capabilities.