Fix various bugs in the moderation feature. (#2608)

* Fix search field string.

* Show your own user as an Admin when changing roles.

* Also show invited users when changing roles.

* Don't allow admin's to kick/ban other admins or themselves.

* Fix a bug when left members were counted as admins/moderators.

* Show when a member is pending.

* Add sections to the change role screen.

ElementX/Sources/Services/Room/RoomMember/RoomMemberProxyProtocol.swift

@@ -31,6 +31,11 @@ protocol RoomMemberProxyProtocol: AnyObject {
 }
 
 extension RoomMemberProxyProtocol {
+    /// The member is active in the room (joined or invited).
+    var isActive: Bool {
+        membership == .join || membership == .invite
+    }
+    
     var permalink: URL? {
         try? PermalinkBuilder.permalinkTo(userIdentifier: userID,
                                           baseURL: ServiceLocator.shared.settings.permalinkBaseURL)