feat: Implement experimental new design

lib/components/default_app_bar_search_field.dart

@@ -9,6 +9,7 @@ class DefaultAppBarSearchField extends StatefulWidget {
   final String hintText;
   final EdgeInsets padding;
   final bool readOnly;
+  final Widget prefixIcon;
 
   const DefaultAppBarSearchField({
     Key key,
@@ -20,6 +21,7 @@ class DefaultAppBarSearchField extends StatefulWidget {
     this.hintText,
     this.padding,
     this.readOnly = false,
+    this.prefixIcon,
   }) : super(key: key);
 
   @override
@@ -73,12 +75,18 @@ class _DefaultAppBarSearchFieldState extends State<DefaultAppBarSearchField> {
         readOnly: widget.readOnly,
         decoration: InputDecoration(
           prefixText: widget.prefixText,
+          enabledBorder: OutlineInputBorder(
+            borderRadius: BorderRadius.circular(12),
+            borderSide:
+                BorderSide(color: Theme.of(context).secondaryHeaderColor),
+          ),
           contentPadding: EdgeInsets.only(
             top: 8,
             bottom: 8,
             left: 16,
           ),
           hintText: widget.hintText,
+          prefixIcon: widget.prefixIcon,
           suffixIcon: !widget.readOnly &&
                   (_focusNode.hasFocus ||
                       (widget.suffix == null &&