Add support for copying a caption. (#3563)

* Add timeline item action for copying a media caption.

* Fix the action colours when long pressing a timeline item.

Nice side effect: Reasonable sized buttons when button shapes are enabled.

* Re-arrange the Timeline Item Menu.

* Add timeline item menu snapshots for media items.

ElementX/Sources/Services/Timeline/TimelineItems/EventBasedMessageTimelineItemProtocol.swift

@@ -35,18 +35,22 @@ extension EventBasedMessageTimelineItemProtocol {
         }
     }
     
-    var hasMediaCaption: Bool {
+    var mediaCaption: String? {
         switch contentType {
         case .audio(let content):
-            content.caption != nil
+            content.caption
         case .file(let content):
-            content.caption != nil
+            content.caption
         case .image(let content):
-            content.caption != nil
+            content.caption
         case .video(let content):
-            content.caption != nil
+            content.caption
         case .emote, .notice, .text, .location, .voice:
-            false
+            nil
         }
     }
+    
+    var hasMediaCaption: Bool {
+        mediaCaption != nil
+    }
 }

ElementX/Sources/Services/Timeline/TimelineItems/EventBasedTimelineItemProtocol.swift

@@ -99,4 +99,14 @@ extension EventBasedTimelineItemProtocol {
             return true
         }
     }
+    
+    var supportsMediaCaption: Bool {
+        guard let messageBasedItem = self as? EventBasedMessageTimelineItemProtocol else { return false }
+        return messageBasedItem.supportsMediaCaption
+    }
+    
+    var hasMediaCaption: Bool {
+        guard let messageBasedItem = self as? EventBasedMessageTimelineItemProtocol else { return false }
+        return messageBasedItem.hasMediaCaption
+    }
 }