feat(nodes): add option to pass a valid target pos / valid source pos func to nodes

* edge updater cannot discern a valid connection by itself so we allow an option to pass a valid connection func to nodes which will then be used to determine if updating connection is valid
* it is optional, by default all connections are valid

Signed-off-by: Braks <78412429+bcakmakoglu@users.noreply.github.com>

src/components/Handle/Handle.vue

@@ -22,7 +22,7 @@ const nodeId = inject(NodeId, '')
 
 const handler = useHandle()
 const onMouseDownHandler = (event: MouseEvent) =>
-  handler(event, props.id, nodeId, props.type === 'target', props.isValidConnection ?? (() => true))
+  handler(event, props.id, nodeId, props.type === 'target', props.isValidConnection)
 </script>
 <script lang="ts">
 export default {