Media loading flow changes (#483)

* Use an imageProvider directly from the view in the home screen

* Add support for media request coalescing

* Rename MediaProxy to MediaLoader

* Add new image loading mechanism to the room details screen avatar.

* Use the `SettingsScreen` prefix for all settings screen related components

* Add new image loading mechanism to the room header

* Add new image loading mechanism to the room member details screen

* Introduce a LoadableImage SwiftUI view that will automatically handle image loading

* Adopt the new LoadableImage where possible

* Fix LoadableImage not using/storing loaded images properly

* Simplify media loader enqueueing

* Made LodableImage load content after mediaSource updates. Adopt it on the home and settings screens

* Introduce a LoadableAvatarImage component and reuse it throughout the app

* Small logging tweaks, made some LoadableImage properties private

* Fix redacted skeletons avatar background color

* Fix placeholder avatars changing when backgrounding the app

* PR comments.

- Trim the @ sign off of mxid placeholders.
- Only expose AvatarSize on the avatar image, use CGSize elsewhere.

Co-authored-by: Doug <douglase@element.io>

ElementX/Sources/Screens/RoomScreen/RoomScreenModels.swift

@@ -49,7 +49,7 @@ enum RoomScreenViewAction {
 struct RoomScreenViewState: BindableState {
     var roomId: String
     var roomTitle = ""
-    var roomAvatar: UIImage?
+    var roomAvatarURL: URL?
     var items: [RoomTimelineViewProvider] = []
     var canBackPaginate = true
     var isBackPaginating = false