refactor(frontend): make plugin support for panels more generic (#11787)

* feat(frontend): add more generic plugin support on PanelGroup

* refactor exsisting use cases

* add plugin panel support to StockLocation
closes https://github.com/inventree/InvenTree/issues/11782

* stop re-using model field

* re-order types

* add panel support for core

* change keys

see https://github.com/inventree/InvenTree/pull/11787#discussion_r3127410867

src/frontend/lib/enums/ModelType.tsx

@@ -38,3 +38,16 @@ export enum ModelType {
   selectionentry = 'selectionentry',
   error = 'error'
 }
+
+export enum PluginPanelKey {
+  // settings / admin
+  admincenter = 'admincenter',
+  systemsettings = 'systemsettings',
+  usersettings = 'usersettings',
+  // generic
+  core = 'core',
+  // landing pages
+  purchasing = 'purchasing',
+  sales = 'sales',
+  manufacturing = 'manufacturing'
+}