chore: migrate deprecation code && code cleanup (#708)

Fixes all issues in `flutter analyze`.
<Reviewed>

Commits:
* chore: migrate deprecated text style

* chore: migrate `toggleableActiveColor` to individual theme

* chore: don't use 'BuildContext's across async gaps

lib/ui/widgets/patchesSelectorView/patch_options_fields.dart

@@ -61,7 +61,7 @@ class OptionsFilePicker extends StatelessWidget {
             child: Text(
               'Select File',
               style: TextStyle(
-                color: Theme.of(context).textTheme.bodyText1?.color,
+                color: Theme.of(context).textTheme.bodyLarge?.color,
               ),
             ),
           ),