Support for changing or removing autolink

Seems that currently you can only **add** `autolink_jira` keywords, not delete or modify. If a project no longer want to autolink a jira keyword they need to file an INFRA issue.

We should implement such that
* if the `autolink_jira` section is removed from `.asf.yaml`, all autolinks are removed
* If the `autolink_jira` section is modified, i.e. one entry removed, then we find what the "diff" is and issue such commands to github

Start by locating the code that reads the .asf.yaml autolink_jira section and issues GitHub autolink commands. Trace how additions are currently handled, then define the diff for removed or changed entries. Done means removing the section removes all autolinks and editing it applies the corresponding removals and updates.

Written by the indexing model from the issue text.