[Limitation] Tchap-web_v4 ignores the incoming room key requests until the cross-signing is supported

[mcalinghee]

After having deactivating cross signing in Tartine, the client does not start the emoji device verification whenever another device requests key exchange.

with iphone

• user has an Tartine session (no other sessions)
• user starts iphone 2.0.5 session
• iphone 2.0.5 requests keys from Tartine.
  → KO. emoji exchange does not start. Tartine seems to receive the event but does not treat it.

with android

• user has an Tartine session (no other sessions)
• user_1 se connecte a android
• android doit demander les clefs à Tartine
  → KO. emoji exchange does not start. Tartine seems to receive the event but does not treat it.

with another web browser

• user_1 est connecté Tartine
• user_1 se connecte à Tartine sur un autre domain (https://app-v4.prod.tchap.incubateur.net/)
• Tartine doit demander les clefs a Tartine
  → KO. emoji exchange does not start. Tartine seems to receive the event but does not treat it.

logs

In each case we have similar logs in Tartine console :
https://www.notion.so/mercurial-timer-ec4/5459adf85ac14e839c68592fa1c71764?v=c890e543e76b492583ebddda5fbe2670

[odelcroi]

KeyRequestHandler.js has been removed. One hint would be to revert it into the projet in order to open the missing dialog.

The dialog has been removed also : https://github.com/matrix-org/matrix-react-sdk/pull/4648/files#diff-a248ba2684dc92f20a3e2eba9f63e28a695f739a1736487a398f6380ba558cf6

EDIT : the dialog does not need to be backported, we should use an existing one : IncomingSasDialog