FIX: Account for different composer 'edit' states in discourse-presence (PR #10631)

Unsure about the approach here. discourse-presence is a plugin, and discourse-shared-edit is also plugin. Whichever way we do this, one plugin will be trying to interface with another. Opening this as a draft for discussion.

GitHub

The title of this pull request changed from “FIX: Allow edit presence indicator to work for discourse-shared-edit” to "FIX: Allow edit presence indicator to work for shared drafts

The title of this pull request changed from “FIX: Allow edit presence indicator to work for shared drafts” to "FIX: Account for different composer ‘edit’ states in discourse-presence