[Story] Receiving requests to join

[mxandreas]

Description

Notifications:

• As an admin who is managing access requests to a room
• I want to be notified when somebody requests access
• So that I am aware that somebody is waiting & they could get a response to their request ASAP

Browsing:

• As an admin who is managing access requests to a room
• I want to be able to browse all the pending requests
• So that I can ensure that no request is missed because I was away or there were a higher number of requests

Conditions:

• The admin here is a user with either invite, kick and/or ban permissions on the room.
• Only the admin should see the requests (including the green dot notification in room list)
  • However, the room is not expected to be bumped to the top when the request lands.
• The section for the pending requests (or generally the ability to accept / decline) should be available for admins only if the room’s join rule is knock or _knockrestricted.

Designs

• Room list: iOS Android Web

Acceptance criteria

• Only users with invite or kick or ban permissions get notified about new requests and can browse existing ones.
• The ability to see existing requests remains available only as long as the room's join rule is knock or _knockrestricted

Size estimate

None

Dependencies

• None

Out of scope

• Nothing

Open questions

### Questions

Subtasks

### Android
- [ ] https://github.com/element-hq/element-x-android/issues/3692

### iOS
- [ ] https://github.com/element-hq/element-x-ios/issues/3422

### Rust
- [ ] https://github.com/matrix-org/matrix-rust-sdk/pull/4170

### Other

[mxandreas]

Based on the discussion I updated the description so that the room is not expected to be bumped to the top of the room list (for the admins) when a new knock on the room arrives. This is left as a stretch goal for the following reasons:

• It is already intentionally not the case for receiving invites for the purpose of not suffering from spamming.
• It is also not trivial to implement this; likely requires server side changes to get a reliable/sustainable implementation.

cc @gaelledel @ganfra