Fix web config trying to set the new prop value as field

Fix the BaseConfigTree treating the nex property name and value boxes as
fields to be applied to the config when pressing Apply.

packages/web_ui/src/components/BaseConfigTree.jsx

@@ -42,6 +42,9 @@ export default function BaseConfigTree(props) {
 		let newChangedFields = new Set(changedFields);
 		let changed = false;
 		for (let [key, value] of Object.entries(changedValues)) {
+			if (key.endsWith(":add.name") || key.endsWith(":add.value")) {
+				continue;
+			}
 			if (initialValues[key] === value) {
 				changed = newChangedFields.delete(key) || changed;
 			} else {