Plugin Directory: Track Ownership

[Ipstenu]

In order to track plugin ownership, it would be beneficial to add a record in the internal comments when a plugin is submitted:

• Submitted by NAME - Profile Link

Then if the plugin OWNER is changed, it could similarly populate a comment:

• Ownership Transferred to NAME - Profile Link

Right now I put those in manually, but having it tracked would allow us to see the history more reliably.

Note: This action can only be performed by admins by design.

[SergeyBiryukov]

In 9094:

Plugin Directory: Track plugin ownership change in audit log.

Props Ipstenu, SergeyBiryukov.
Fixes #4663.