feat: refactor code highlighting and add scripts editor pane

- replace `flutter_highlighter` and `highlighter` with `flutter_highlight` and `highlight`.
- add `flutter_code_editor` dependency.
- introduce a new scripts editor pane in the REST request view.

lib/widgets/scripts_editor_pane.dart

@@ -0,0 +1,44 @@
+import 'package:apidash/providers/settings_providers.dart';
+import 'package:flutter/material.dart';
+import 'package:flutter_code_editor/flutter_code_editor.dart';
+import 'package:flutter_highlight/themes/monokai.dart';
+import 'package:flutter_highlight/themes/xcode.dart';
+import 'package:flutter_riverpod/flutter_riverpod.dart';
+
+class ScriptsEditorPane extends ConsumerStatefulWidget {
+  final CodeController controller;
+  const ScriptsEditorPane({super.key, required this.controller});
+
+  @override
+  ConsumerState<ScriptsEditorPane> createState() => _ScriptsEditorPaneState();
+}
+
+class _ScriptsEditorPaneState extends ConsumerState<ScriptsEditorPane> {
+  @override
+  Widget build(BuildContext context) {
+    final settings = ref.watch(settingsProvider);
+    return CodeTheme(
+      data: CodeThemeData(
+        styles: settings.isDark ? monokaiTheme : xcodeTheme,
+      ),
+      child: SingleChildScrollView(
+        child: CodeField(
+          smartDashesType: SmartDashesType.enabled,
+          smartQuotesType: SmartQuotesType.enabled,
+          background: Theme.of(context).colorScheme.surfaceContainerLowest,
+          gutterStyle: GutterStyle(
+            width: 40, // TODO: Fix numbers size
+            margin: 2,
+            textAlign: TextAlign.left,
+          ),
+          cursorColor: Theme.of(context).colorScheme.primary,
+          controller: widget.controller,
+          textStyle: TextStyle(
+            fontSize: 12,
+            fontFamily: 'monospace',
+          ),
+        ),
+      ),
+    );
+  }
+}