- previously, we'd display the bubble only when joining the community
- now we display it also when editing the shared addresses, with a
slightly different wording (eg. "You're an admin" -> "You'll be a
member"), hinting the user about the future change
- remove the usage of `ModuleWarning` as we don't want its delay or
transitions here, replace it with a regular red `Rectangle` + text
Fixes#13397
ea40a6b11f