add twitter api

lib/twitter/twitter_api.dart

@@ -0,0 +1,37 @@
+import 'dart:convert';
+import 'package:cake_wallet/twitter/twitter_user.dart';
+import 'package:http/http.dart' as http;
+import 'package:cake_wallet/.secrets.g.dart' as secrets;
+
+class TwitterApi {
+  static const twitterBearerToken = secrets.twitterBearerToken;
+  static const httpsScheme = 'https';
+  static const apiHost = 'api.twitter.com';
+  static const userPath = '/2/users/by/username/';
+
+  static Future<TwitterUser> lookupUserByName({required String userName}) async {
+    final queryParams = {'user.fields': 'description'};
+
+    final headers = {'authorization': 'Bearer ${secrets.twitterBearerToken}'};
+
+    final uri = Uri(
+      scheme: httpsScheme,
+      host: apiHost,
+      path: userPath + userName,
+      queryParameters: queryParams,
+    );
+
+    var response = await http.get(uri, headers: headers);
+
+    if (response.statusCode != 200) {
+      throw Exception('Unexpected http status: ${response.statusCode}');
+    }
+    final responseJSON = json.decode(response.body) as Map<String, dynamic>;
+
+    if (responseJSON['errors'] != null) {
+      throw Exception(responseJSON['errors'][0]['detail']);
+    }
+
+    return TwitterUser.fromJson(responseJSON['data'] as Map<String, dynamic>);
+  }
+}