PUBLISH Bulk Operation when working on imported changesets

Created by: BolajiOlajide

When working with imported changesets, users get the PUBLISH bulk operation when an imported changeset is selected, this always leads to an error because we don't allow publishing of imported changesets.

It might be better if we disable publishing when querying for available bulk operations on an imported changesets. Question, is how do we recognize imported changesets at the point where they're being displayed?

Context - https://sourcegraph.slack.com/archives/CMMTWQQ49/p1656447528013549