JIRA integration helper bot/GHA

[jmtd]

We ask the following of PRs https://github.com/jboss-container-images/openjdk/blob/ubi9/.github/PULL_REQUEST_TEMPLATE.md

Some of this could be assisted by a GHA action

1. detect missing JIRA issue URI, flag via label
2. detect misisng JIRA issue reference in Subject, flag via label
3. if 1) or 2) is present but not the other, populate one from the other
4. flag (via label) and/or block merging if commits w/o Signed-off-by present

Potentially we could go further: track linked JIRA issue state changes; auto-raise JIRA mirror issue...