chore: add smoke test for git-sync [INS-4132]

[filfreire]

Closes INS-4132

Adds a basic prerelease test where we clone, checkout a different branch, and commit changes, while checking local history.

Pull and push are not in the initial implementation, but there is a way, pending discussion with rest of @Kong/team-insomnia:

• We can define GH actions secret, with a GH access token with enough permissions to push a commit to a branch
• Pass that access token on the GH prerelease test workflow as a env variable (see doc)
• And checkout a designated separate branch of insomnia-git-example where we push a commit with a timestamp or a UUID to check pushing works ok.

Pros/cons - it would be overkill for regular smoke checks, but for prerelease ones I believe it's acceptable.

[jackkav]

Move it to smoke tests and we are cooking 🧑‍🍳