cursor: avoid sending unnecessary pointer motion events

If the current Cursor.maybeResetState() function is called while in
passthrough mode, it will send a pointer motion event. This is
unnecessary as we have already sent the same pointer motion event at
least once.

Also refactor the code slightly and improve naming.

river/Root.zig

@@ -405,7 +405,7 @@ fn commitTransaction(self: *Self) void {
 
         output.damage.addWhole();
     }
-    server.input_manager.maybeResetCursorState();
+    server.input_manager.updateCursorState();
 }
 
 /// Send the new output configuration to all wlr-output-manager clients