Fix DropdownInput widget not reactively updating when its content changes (#2770)

* Improve reactivity of DropdownInput.svelte

* Fix formatting lint

---------

Co-authored-by: Keavon Chambers <keavon@keavon.com>

frontend/src/components/widgets/inputs/DropdownInput.svelte

@@ -30,6 +30,7 @@
 	let open = false;
 
 	$: watchSelectedIndex(selectedIndex);
+	$: watchEntries(entries);
 	$: watchActiveEntry(activeEntry);
 	$: watchOpen(open);
 
@@ -38,7 +39,13 @@
 	}
 
 	// Called only when `selectedIndex` is changed from outside this component
-	function watchSelectedIndex(_?: number) {
+	function watchSelectedIndex(_?: typeof selectedIndex) {
+		activeEntrySkipWatcher = true;
+		activeEntry = makeActiveEntry();
+	}
+
+	// Called only when `entries` is changed from outside this component
+	function watchEntries(_?: typeof entries) {
 		activeEntrySkipWatcher = true;
 		activeEntry = makeActiveEntry();
 	}