Render kick and ban reason in the timeline when available (#4642)

* Map the reason to RoomMembershipContent

* Create function to create RoomMembershipContent.

* Render reason for kick and ban state event.

libraries/matrix/api/src/main/kotlin/io/element/android/libraries/matrix/api/timeline/item/event/EventContent.kt

@@ -70,7 +70,8 @@ data class UnableToDecryptContent(
 data class RoomMembershipContent(
     val userId: UserId,
     val userDisplayName: String?,
-    val change: MembershipChange?
+    val change: MembershipChange?,
+    val reason: String?,
 ) : EventContent
 
 data class ProfileChangeContent(