DM: Session end deep-link

[Johennes]

For element-hq/element-web#26000 to fully function we'll need support on the MAS side to perform the logout of a session in response to a deeplink navigation.

https://github.com/matrix-org/matrix-spec-proposals/blob/hughns/sso-redirect-action/proposals/3824-oidc-aware-clients.md#definition-of-oidc-aware proposes the convention of ?action=session_end&device_id=<device_id>.

ACs

• The deep link set up in EW: Direct to MAS for sign-out in OIDC-aware mode element-hq/element-web#26000:
  • Loads the session's details page
  • Causes the respective sessions to be signed out after confirming a dialog
• TBD: How are we gonna reflect that the sign-out happened in the UI?

Blocks on #1640

[hughns]

EW develop/nightly is now generating appropriately formatted deep links which could be used for testing.