Modern Label printing (#724)

* Basic widget

* Redirect label printing action

* Refactor label printing code

* Construct form elements

* Refactor to allow re-use of forms

* Basic rendering of label printing form

* Remove dead code

* Pass custom handler through to form context

* Refactoring API forms:

- Allow custom pk field name
- Add callback when values change

* linting

* Dynamically rebuild form

* Handle nested fields

* Handle label printing status

* Run dart format

* Update release notes

* Remove unused var

* Enable close icon

* Handle initial plugin default value

* Store default values:

- Selected template (per label type)
- Selected printing plugin

* Dart format

* Fix dart linting

* use setter

* Just use a public field

lib/widget/stock/location_display.dart

@@ -38,7 +38,7 @@ class _LocationDisplayState extends RefreshableState<LocationDisplayWidget> {
 
   final InvenTreeStockLocation? location;
 
-  List<Map<String, dynamic>> labels = [];
+  bool allowLabelPrinting = false;
 
   @override
   String getAppBarTitle() {
@@ -179,19 +179,15 @@ class _LocationDisplayState extends RefreshableState<LocationDisplayWidget> {
       );
     }
 
-    if (widget.location != null && labels.isNotEmpty) {
+    if (widget.location != null &&
+        allowLabelPrinting &&
+        api.supportsModernLabelPrinting) {
       actions.add(
         SpeedDialChild(
           child: Icon(TablerIcons.printer),
           label: L10().printLabel,
           onTap: () async {
-            selectAndPrintLabel(
-              context,
-              labels,
-              widget.location!.pk,
-              "location",
-              "location=${widget.location!.pk}",
-            );
+            selectAndPrintLabel(context, "stocklocation", widget.location!.pk);
           },
         ),
       );
@@ -236,33 +232,10 @@ class _LocationDisplayState extends RefreshableState<LocationDisplayWidget> {
       }
     }
 
-    List<Map<String, dynamic>> _labels = [];
-    bool allowLabelPrinting = await InvenTreeSettingsManager().getBool(
+    allowLabelPrinting = await InvenTreeSettingsManager().getBool(
       INV_ENABLE_LABEL_PRINTING,
       true,
     );
-    allowLabelPrinting &= api.supportsMixin("labels");
-
-    if (allowLabelPrinting) {
-      if (widget.location != null) {
-        String model_type = api.supportsModernLabelPrinting
-            ? InvenTreeStockLocation.MODEL_TYPE
-            : "location";
-        String item_key = api.supportsModernLabelPrinting
-            ? "items"
-            : "location";
-
-        _labels = await getLabelTemplates(model_type, {
-          item_key: widget.location!.pk.toString(),
-        });
-      }
-    }
-
-    if (mounted) {
-      setState(() {
-        labels = _labels;
-      });
-    }
   }
 
   Future<void> _newLocation(BuildContext context) async {