Close the invite screen once the invite has been declined (#7440)

Declining an invite from the full screen invite left the user on that
same screen, so they had to press back themselves to get to the room
list. Both decline paths are affected: the plain decline handled by
AcceptDeclineInviteView, and the decline and block sub screen, which
navigated up into the join room flow instead of out of it.

Navigate up from the join room flow on a successful decline, and give
DeclineInviteAndBlockEntryPoint a callback so the sub screen can report
a successful decline separately from a back press. The room list flow
supplies the same callback, popping the sub screen once the invite has
been declined.

features/joinroom/impl/src/main/kotlin/io/element/android/features/joinroom/impl/JoinRoomFlowNode.kt

@@ -69,6 +69,9 @@ class JoinRoomFlowNode(
                 parentNode = this,
                 buildContext = buildContext,
                 inviteData = navTarget.inviteData,
+                callback = object : DeclineInviteAndBlockEntryPoint.Callback {
+                    override fun onDeclineSuccess() = navigateUp()
+                },
             )
             NavTarget.Root -> rootNode(buildContext)
         }
@@ -99,7 +102,7 @@ class JoinRoomFlowNode(
             acceptDeclineInviteView.Render(
                 state = state.acceptDeclineInviteState,
                 onAcceptInviteSuccess = {},
-                onDeclineInviteSuccess = {},
+                onDeclineInviteSuccess = { navigateUp() },
                 modifier = Modifier
             )
         }