Server Quota Notices in Riot - Step 2

[bmarty]

Finish what has been started in #2440:

• Manage banner for people who haven't been locked out (the blue one)
• Store the MatrixError in the session to prevent user from being able to send message when entering in the room and before the sync complete
• Handle the issue during the registration. Currently there is a Toast when skipping the email/phone number form

[bmarty]

3rd point (registration) has been treated on version 0.8.14

[bmarty]

Done