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>

UITests/Sources/RoomScreenUITests.swift

@@ -24,7 +24,7 @@ class RoomScreenUITests: XCTestCase {
         app.goToScreenWithIdentifier(.roomPlainNoAvatar)
 
         XCTAssert(app.staticTexts["roomNameLabel"].exists)
-        XCTAssert(app.staticTexts["roomAvatarPlaceholderImage"].exists)
+        XCTAssert(app.staticTexts["roomAvatarImage"].exists)
 
         app.assertScreenshot(.roomPlainNoAvatar)
     }