[Spaces] M10.4 SDK: Filter rooms for a given space

[SBiOSoftWhare]

Get all child rooms for a given space

TODO:

• In RoomSummary:
  • Add and support spaceChildren: [MXSpaceChildInfo] property
  • Add flattenParentIds property if needed like Android in order to knows ancestor ids and cache the result.
    • Compute flattenParentIds after each sync like Android? In background. Android algorithm: https://github.com/vector-im/element-android/blob/72b1bd354e24888094aa02c8c6d7971a82cd807d/matrix-sdk-android/src/main/java/org/matrix/android/sdk/internal/session/room/summary/RoomSummaryUpdater.kt#L198
• Rooms filtering
  • Make some R&D around room filtering
  • MXSession should not keep filtering state
  • If needed create an MXRoomList behaves like MXTimeline, with listeners, filters, asynchronous. Room data sources should use directly these MXRoomList.
    • For left panel space list to get root spaces: Filter room with type m.space where MXRoomSummary.flattenParentIds is empty or nil.
    • For room list: Filter rooms with type m.message or nil.