Send ClientVersionUpdatedEvent for each client state change, not only on version updates

as discussed in the chat https://chat.briarproject.org/briar/pl/1n8cpis8mjy55ci7sekih1i8aw

tested to work with Briar Desktop, but not yet with Briar Android. quoting @akwizgran

we'd also need to test that this didn't break the scenario where a contact upgrades to a version of briar that supports images/self-destructing messages, while we have the conversation screen already open

Not sure how to best test this, there might be an integration test for it already? In case anyone feels like it, I would appreciate your help in testing.