Barcode refactor (#363)

* Move barcode.dart

* Fix

* Refactoring barcode scanner code:

- Abstract the "controller" class (for future development)
- Break barcode scanning code out into multiple files
- Add CameraBarcodeController class (qr_code_scanner)

* Add await

* Make barcode scan delay configurable

* remove unused import

* Handle camera exceptions

* Improve sequencing for camera scanner

- Show loading overlay
- Prevent reload if view is no longer mounted

* Update docstring

* Update release notes

lib/l10n/app_en.arb

@@ -79,6 +79,12 @@
   "availableStock": "Available Stock",
   "@availableStock": {},
 
+  "barcodes": "Barcodes",
+  "@barcodes": {},
+
+  "barcodeSettings": "Barcode Settings",
+  "@barcodeSettings": {},
+
   "barcodeAssign": "Assign Barcode",
   "@barcodeAssign": {},
 
@@ -106,6 +112,12 @@
   "barcodeScanAssign": "Scan to assign barcode",
   "@barcodeScanAssign": {},
 
+  "barcodeScanDelay": "Barcode Scan Delay",
+  "@barcodeScanDelay": {},
+
+  "barcodeScanDelayDetail": "Delay between barcode scans",
+  "@barcodeScanDelayDetail": {},
+
   "barcodeScanGeneral":  "Scan an InvenTree barcode",
   "@barcodeScanGeneral": {},