Support Phorge as an external issue tracker

What does this MR do and why?

Support Phorge, the community successor/fork of Phabricator, as an issue tracker.

Supports the Maniphest task ID format used by Phorge.

• T123

MR acceptance checklist

Please evaluate this MR against the MR acceptance checklist. It helps you analyze changes to reduce risks in quality, performance, reliability, security, and maintainability.

Screenshots or screen recordings

Screenshots are required for UI changes, and strongly recommended for all other merge requests.

How to set up and validate locally

Numbered steps to set up and validate the change are strongly suggested.

1. Configure a Phorge integration for your test project using the values from the screenshot.
2. Create a new commit and reference T123 in the commit message.
3. Push the commit.
4. View the commit in UI and verify that the "T123" string renders as a link to the configured Phorge website. -->