GitStream assumes it is operating in a GitHub context

[echarrod]

Describe the bug

For the line in a MR:

Check for MR: `glab mr list --source-branch=$(git branch --show-current)`

GitStream reports incorrectly that we should use GitHub tools, and that GitLab ones are invalid:

🪲 Bug - GitLab Tool Usage: Replace the glab command with gh (GitHub CLI) commands appropriate for GitHub environments, or make the tooling configurable based on the git hosting platform.

To Reproduce

Steps to reproduce the behavior:

1. Run docker version of GitStream on GitLab
2. Change/add commands that are applicable to GitLab, not GitHub
3. Create MR

Expected behavior

• GitStream should have context about what hosting platform it is running on, and should work out that GitLab commands are correct for GitLab repos

Screenshots

Additional context

• MR link: https://gitlab.com/lunomoney/product-engineering/core/-/merge_requests/70251
• Running gitStream Docker image version: v1.0.158