fix: trigger jobs can be executed and retried

Description

Fix to allow trigger jobs to be executed or retried from the GitLab Workflow extension for VSCode.

Related Issues

Resolves #2170 (closed)

How has this been tested?

Automated unit tests are included for

• Manual trigger job has execute command
• Finished trigger job has retry command
• Running trigger job does not have cancel command

Also, tested locally following the documented procedure to test the extension. Tested the following scenarios

• For a manual trigger job which has not yet run, can right-click and execute the job. If done, the trigger job will run.
• For a trigger job which has finished, can right-click and retry the job. If done, the trigger job will retry.
• Left clicking on a trigger job does not open anything in the editor (as before, as expected, trigger jobs do not have a trace)
• Right-clicking on a running trigger job does not allow a cancel (trigger jobs cannot be cancelled in the same way that other jobs can)
• A trigger job which is waiting for previous stages to complete will show as Created and cannot be executed (as before, not changed)

Screenshots (if appropriate)

What CHANGELOG entry will this MR create?

• fix: Bug fix fixes - a user-facing issue in production - included in changelog