feat: impl job resume

[shiyasmohd]

• Implemented job resume functionality in scheduler & worker for jobs in STOPPED state.
• Added admin-api endpoint PUT /jobs/{id}/resume to resume a job.
• Added ampctl job resume command to resume jobs via admin-api
• Added tests for job resume endpoint in admin-api

Closes #1058

[LNSD]

In my opinion, we should not restart a job that is already in a terminal state, such as STOPPED.

Furthermore, I don't see a point in adding a pause/resume mechanism to the jobs, given that the underlying worker logic doesn't support those actions.

In my opinion, we should put the "pause and resume jobs" feature request on hold until we have a better understanding of what operator use cases this would cover.

[leoyvens]

Maybe we should rename it to ampctl job start? The behaviour seems useful for manual restarts. wdyt @LNSD