Change from fontawesome to tabler icons (#516)

* Change from fontawesome to tabler icons

- Consistent with the frontend

* Cleanup conflicts

* Use double quotes

* remove unused import

* Update release notes

* Migrate some google icons to tabler icons

* Icon update

* Properly support display of custom icons

* Fix lookup

lib/widget/spinner.dart

@@ -1,6 +1,4 @@
 import "package:flutter/material.dart";
-
-import "package:font_awesome_flutter/font_awesome_flutter.dart";
 import "package:inventree/app_colors.dart";
 
 class Spinner extends StatefulWidget {
@@ -31,7 +29,7 @@ class _SpinnerState extends State<Spinner> with SingleTickerProviderStateMixin {
       duration: Duration(milliseconds: 2000),
     )
       ..repeat();
-    _child = FaIcon(
+    _child = Icon(
       widget.icon,
       color: widget.color
     );