fix(gitlab): add support for nested groups/subgroups

[wescrow]

Description

This PR adds support for GitLab repositories organized in nested group structures (e.g., owner/subgroup/repo).

Summary

The existing GitLab integration only handled top-level groups (owner/repo), causing 404 errors when attempting to
connect repositories in nested groups. This was due to incomplete project path encoding in the GitLab API calls.

Changes

• Added encodeProjectPath() helper method to properly URL-encode all path segments in project paths
• Fixed getRepository() method to extract the full project path from git URLs instead of just owner/repo
• Updated API calls in multiple methods to use properly encoded paths:
  • addWebhook() - webhook creation and listing
  • addDeployKey() - deploy key creation
  • getBranches() - branch listing
  • getReferences() - branch, tag, and commit listing

Example

For a repository like git@gitlab.com:owner/subgroup/repo.git:

Before: API call to projects/owner/subgroup%2Frepo → 404 error
After: API call to projects/owner%2Fsubgroup%2Frepo → success

The issue was that forward slashes in the owner path (from nested groups) weren't being encoded, resulting in
malformed API paths.

Fixes #728

Type of change

• Bug fix (non-breaking change which fixes an issue)

How Has This Been Tested?

Tested extensively in a production Kubernetes environment:

1. Built custom Docker image from fork: wescrow/kubero:fix-gitlab-nested-groups
2. Deployed to Kubernetes cluster running on AWS EKS
3. Successfully connected GitLab repository in 3-level nested group structure
4. Verified full workflow:
   • Repository connection and authentication
   • Deploy key creation
   • Webhook configuration
   • Branch listing and selection
   • Application deployment via Runpacks

The fix has been running in production for several hours without issues.

Test Configuration:

• Kubernetes Version: 1.29+ (AWS EKS)
• GitLab: gitlab.com (SaaS)
• Repository: 3-level nested group structure
• Test Image: wescrow/kubero:fix-gitlab-nested-groups (available on Docker Hub)

Checklist:

• I removed unnecessary debug logs
• My code follows the style guidelines of this project
• I have performed a self-review of my code
• I documented my code, particularly in hard-to-understand areas
• My changes generate no new warnings