Enable the media browser feature 🖼️ (#3642)

* Overlay a progress indicator for downloads instead of using a toast indicator.

* Update the SDK.

* Remove the feature flag for the media browser.

* Remove the media captions feature flag too.

* Add unit test cases for download failure and swiping between items.

* Snapshots (with the media browser visible in the screen).

ElementX/Sources/Screens/Timeline/TimelineViewModel.swift

@@ -81,7 +81,6 @@ class TimelineViewModel: TimelineViewModelType, TimelineViewModelProtocol {
                                                        timelineState: TimelineState(focussedEvent: focussedEventID.map { .init(eventID: $0, appearance: .immediate) }),
                                                        ownUserID: roomProxy.ownUserID,
                                                        isViewSourceEnabled: appSettings.viewSourceEnabled,
-                                                       isCreateMediaCaptionsEnabled: appSettings.createMediaCaptionsEnabled,
                                                        hideTimelineMedia: appSettings.hideTimelineMedia,
                                                        pinnedEventIDs: roomProxy.infoPublisher.value.pinnedEventIDs,
                                                        bindings: .init(reactionsCollapsed: [:]),
@@ -449,10 +448,6 @@ class TimelineViewModel: TimelineViewModelType, TimelineViewModelProtocol {
             .weakAssign(to: \.state.isViewSourceEnabled, on: self)
             .store(in: &cancellables)
         
-        appSettings.$createMediaCaptionsEnabled
-            .weakAssign(to: \.state.isCreateMediaCaptionsEnabled, on: self)
-            .store(in: &cancellables)
-        
         appSettings.$hideTimelineMedia
             .weakAssign(to: \.state.hideTimelineMedia, on: self)
             .store(in: &cancellables)