Add "Arisa" project for messages that are usually only used by Arisa.

[MikeUnverferth]

This will shorten the selection list for the other projects.

[NeunEinser]

@SPGoding pinging you since you implemented these things over on Arisa.
If I understand correctly, currently this is not possible, as Arisa always looks for the correct message depending on the project. I think it would be good to create a mirror of this issue on the Arisa project to highlight the changes that would be needed on Arisa's side.

[MikeUnverferth]

Alternatively instead of changing Arisa to look in another "project", we could have a way to simply exclude the Arisa-only messages from the selection list.

[dericksonmark]

Several messages are present in the messages.yml file that are not shown in the dropdown. This is achieved by adding hidden: true to their definition. It appears as if you made this issue after this feature was implemented (June 20, 2020), however. Has this since been resolved?

[SPGoding]

Yeah this is already a thing now. For example, the "I am a bot" message is hidden from the selection list. Do you think there are other messages that should be hidden?