Fix some incorrect flutter whitespace

Author: stnguyen90

templates/flutter/lib/src/client_base.dart.twig

@@ -5,7 +5,7 @@ import 'enums.dart';
 abstract class ClientBase implements Client {  
 {% for header in spec.global.headers %}
 {% if header.description %}
-    /// {{header.description}}
+  /// {{header.description}}
 {% endif %}
   @override
   ClientBase set{{header.key | caseUcfirst}}(value);

templates/flutter/lib/src/client_browser.dart.twig

@@ -45,7 +45,7 @@ class ClientBrowser extends ClientBase with ClientMixin {
       'x-sdk-language': '{{ language.name | caseLower }}',
       'x-sdk-version': '{{ sdk.version }}',
 {% for key,header in spec.global.defaultHeaders %}
-      '{{key}}' : '{{header}}',
+      '{{key}}': '{{header}}',
 {% endfor %}
     };
 
@@ -61,14 +61,14 @@ class ClientBrowser extends ClientBase with ClientMixin {
 
 {% for header in spec.global.headers %}
 {% if header.description %}
-     /// {{header.description}}
+  /// {{header.description}}
 {% endif %}
-    @override
-    ClientBrowser set{{header.key | caseUcfirst}}(value) {
-        config['{{ header.key | caseCamel }}'] = value;
-        addHeader('{{header.name}}', value);
-        return this;
-    }
+  @override
+  ClientBrowser set{{header.key | caseUcfirst}}(value) {
+    config['{{ header.key | caseCamel }}'] = value;
+    addHeader('{{header.name}}', value);
+    return this;
+  }
 {% endfor %}
 
   @override
@@ -197,7 +197,7 @@ class ClientBrowser extends ClientBase with ClientMixin {
       final cookieFallback = res.headers['x-fallback-cookies'];
       if (cookieFallback != null) {
         debugPrint(
-            'Appwrite is using localStorage for session management. Increase your security by adding a custom domain as your API endpoint.');
+            '{{spec.title | caseUcfirst}} is using localStorage for session management. Increase your security by adding a custom domain as your API endpoint.');
         addHeader('X-Fallback-Cookies', cookieFallback);
         html.window.localStorage['cookieFallback'] = cookieFallback;
       }
@@ -214,7 +214,7 @@ class ClientBrowser extends ClientBase with ClientMixin {
   Future webAuth(Uri url, {String? callbackUrlScheme}) {
   return FlutterWebAuth2.authenticate(
       url: url.toString(),
-      callbackUrlScheme: "appwrite-callback-" + config['project']!,
+      callbackUrlScheme: "{{spec.title | caseLower}}-callback-" + config['project']!,
     );
   }
 }