Update GitIgnore

- Update Flutter generated GitIgnore.

Author: rayliverified

.gitignore

@@ -8,6 +8,7 @@
 .buildlog/
 .history
 .svn/
+migrate_working_dir/
 
 # IntelliJ related
 *.iml
@@ -21,27 +22,9 @@
 #.vscode/
 
 # Flutter/Dart/Pub related
+# Libraries should not include pubspec.lock, per https://dart.dev/guides/libraries/private-files#pubspeclock.
+/pubspec.lock
 **/doc/api/
-**/ios/Flutter/.last_build_id
 .dart_tool/
-.flutter-plugins
-.flutter-plugins-dependencies
 .packages
-.pub-cache/
-.pub/
-/build/
-pubspec.lock
-
-# Web related
-lib/generated_plugin_registrant.dart
-
-# Symbolication related
-app.*.symbols
-
-# Obfuscation related
-app.*.map.json
-
-# Android Studio will place build artifacts here
-/android/app/debug
-/android/app/profile
-/android/app/release
+build/