Sales order support (#438)

* Add new models for SalesOrder

- Create generic Order and OrderLine models with common functionality

* Refactor

- Move some widgets around
- Cleanup directory structure

* Add link to home screen and nav drawer

* Add SalesOrder list widget

* Linting fixes

* Fix string

* Refactor PurchaseOrderDetailWidget

* Tweaks to existing code

* linting

* Fixes for drawer widget

* Add "detail" page for SalesOrder

* Add more tiles to SalesOrder detail

* Allow editing of salesorder

* add list filters for sales orders

* Display list of line items

* Customer updates

- Display customer icon on home screen
- Fetch sales orders for customer detail page

* Cleanup company detail view

* Create new sales order from list

* Stricter typing for formFields method

* Create new PurchaseOrder and SalesOrder from company deatil

* Status code updates

- Add function for name comparison
- Remove hard-coded values

* Update view permission checks for home widget

* Add ability to manually add SalesOrderLineItem

* Add nice progress bar widgets

* Display detail view for sales order line item

* edit SalesOrderLineItem

* Fix unused import

* Hide "shipped items" tab

- Will be added in a future update

lib/widget/part/part_image_widget.dart

@@ -0,0 +1,78 @@
+import "dart:io";
+
+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/fields.dart";
+import "package:inventree/widget/refreshable_state.dart";
+import "package:inventree/widget/snacks.dart";
+import "package:inventree/l10.dart";
+
+class PartImageWidget extends StatefulWidget {
+
+  const PartImageWidget(this.part, {Key? key}) : super(key: key);
+
+  final InvenTreePart part;
+
+  @override
+  _PartImageState createState() => _PartImageState(part);
+
+}
+
+
+class _PartImageState extends RefreshableState<PartImageWidget> {
+
+  _PartImageState(this.part);
+
+  final InvenTreePart part;
+
+  @override
+  Future<void> request(BuildContext context) async {
+    await part.reload();
+  }
+
+  @override
+  String getAppBarTitle() => part.fullname;
+
+  @override
+  List<Widget> appBarActions(BuildContext context) {
+
+    List<Widget> actions = [];
+
+    if (part.canEdit) {
+
+      // File upload
+      actions.add(
+        IconButton(
+          icon: FaIcon(FontAwesomeIcons.fileArrowUp),
+          onPressed: () async {
+
+            FilePickerDialog.pickFile(
+              onPicked: (File file) async {
+                final result = await part.uploadImage(file);
+
+                if (!result) {
+                  showSnackIcon(L10().uploadFailed, success: false);
+                }
+
+                refresh(context);
+              }
+            );
+
+          },
+        )
+      );
+    }
+
+    return actions;
+  }
+
+  @override
+  Widget getBody(BuildContext context) {
+    return InvenTreeAPI().getImage(part.image);
+  }
+
+}