New library names to publish forked by AngularDart Community packages

[IgorBabalich]

This task is a part of AngularDart 8 Roadmap

Rename forked by AngularDart Community packages to be able publish and use them on pub.dev

New package names:
angular -> ngdart (the existing ngdart package utility will be renamed to ngdart_cli)
angular_ast -> ngast
angular_compiler -> ngcompiler
angular_forms -> ngforms
angular_router -> ngrouter
angular_test -> ngtest

Dart SDK: 2.17.0
AngularDart Version: 8.0.0

[GZGavinZhao]

Go ahead :)