Support for Atlassian's Jira

By @AlexDHoffer: https://github.com/argoproj-labs/argocd-notifications/issues/240

Some existing CD systems e.g. Jenkins can post build results to Jira issues as well as natively link commits in the build to those issues. See here for details: https://plugins.jenkins.io/jira/

This is a slick feature for a CD system and since Atlassian's Jira is in such widespread usage these days it would be cool to have something similar, where ArgoCD can key off a Jira issue tag in a commit message and post when a successful sync of that tag occurred back to the issue itself in Jira.

Start by reading the linked argocd-notifications issue and the Jenkins Jira plugin details to clarify the expected integration. Define how a Jira issue tag in a commit is identified and how a successful sync posts its result back to Jira, including commit linking; done means this flow is specified and works reliably.

Written by the indexing model from the issue text.