* core: add chat items to indicate decryption failures due to ratchets being out of sync
* show ratchet errors in chat items, show all integrity errors
* show decryption errors, tests
* ios: chat items, remove item for duplicate messages
* android: decryption errors chat items
* eol
* core: initial group member role when joining via link
* fix tests
* set role when joining group via link, enable observer test
* show group link when role changes
* amend test
* check role is member or observer when creating a link