Timeline item sender profiles (#463)

* Adopt timeline item sender profiles for displaying user avatars and display names
* Prevent images from automatically being evicted from the in-memory cache when entering background
* Get rid of all the `urlString: String`s and start using proper URLs
* Add back manual display name loading as the sender profiles aren't working properly yet
* Implement a sender profile.
* Bump the RustSDK to v1.0.32-alpha

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

ElementX/Sources/Services/Client/ClientProxyProtocol.swift

@@ -83,7 +83,7 @@ protocol ClientProxyProtocol: AnyObject, MediaProxyProtocol {
     
     func loadUserDisplayName() async -> Result<String, ClientProxyError>
         
-    func loadUserAvatarURLString() async -> Result<String, ClientProxyError>
+    func loadUserAvatarURL() async -> Result<URL, ClientProxyError>
     
     func accountDataEvent<Content: Decodable>(type: String) async -> Result<Content?, ClientProxyError>
     
@@ -101,7 +101,7 @@ protocol ClientProxyProtocol: AnyObject, MediaProxyProtocol {
                    deviceDisplayName: String,
                    profileTag: String?,
                    lang: String,
-                   url: String?,
+                   url: URL?,
                    format: PushFormat?,
                    defaultPayload: [AnyHashable: Any]?) async throws
 }