Enable multi-line text editing for API forms

- User can edit part notes
- User can edit stock item notes

lib/widget/part_notes.dart

@@ -1,9 +1,14 @@
+import 'package:flutter/material.dart';
+import 'package:font_awesome_flutter/font_awesome_flutter.dart';
+import 'package:inventree/api.dart';
 import 'package:inventree/inventree/part.dart';
 import 'package:inventree/widget/refreshable_state.dart';
 import 'package:flutter/cupertino.dart';
 import 'package:flutter_markdown/flutter_markdown.dart';
 import 'package:inventree/l10.dart';
 
+import '../api_form.dart';
+
 
 class PartNotesWidget extends StatefulWidget {
 
@@ -22,9 +27,47 @@ class _PartNotesState extends RefreshableState<PartNotesWidget> {
 
   _PartNotesState(this.part);
 
+  @override
+  Future<void> request() async {
+    await part.reload();
+  }
+
   @override
   String getAppBarTitle(BuildContext context) => L10().partNotes;
 
+  @override
+  List<Widget> getAppBarActions(BuildContext context) {
+
+    List<Widget> actions = [];
+
+    if (InvenTreeAPI().checkPermission('part', 'change')) {
+      actions.add(
+        IconButton(
+          icon: FaIcon(FontAwesomeIcons.edit),
+          tooltip: L10().edit,
+          onPressed: () {
+            launchApiForm(
+              context,
+              L10().editNotes,
+              part.url,
+              {
+                "notes": {
+                  "multiline": true,
+                }
+              },
+              modelData: part.jsondata,
+              onSuccess: () async {
+                refresh();
+              }
+            );
+          }
+        )
+      );
+    }
+
+    return actions;
+  }
+
   @override
   Widget getBody(BuildContext context) {
     return Markdown(