Support Per-Repository Authentication Settings

[LucasMrqes]

Currently, the controller uses a single set of credentials for all GitHub or GitLab repositories it interacts with. This approach poses challenges when dealing with multiple GitHub/GitLab organizations or several GitLab projects that require distinct tokens.
This is not a problem for planning/applying layers, since the git authentication is passed to the runner distinctly ; this is a problem for adding comments to MR / PR.

The controller should use a default token, but could eventually use one specified within the TerraformRepository specification (with a reference to a Kubernetes secret or specify a token directly)

To go further: the issue is the same for the webhook token, however a workaround is to always use the same (not ideal)