Added support for Angular 9

[bbergquist0930]

This is working for Angular 9. I am no Angular expert and I question if the build plugin index.ts can be cleaned up more where it is generating the main.ts but your example is working now under Angular 9.

I started with a new project created with ng new and moved over your files from the cli8 branch and pieced it together so that is why there are changed to things like tslint.json.

[deepakrobot]

@bbergquist0930 @alexzuza Thanks for updating the ivy related changes. Is it possible to load plugins developed in ng8 to load in ivy (ng9 or above)? I tried to load but get following error:

ERROR Error: Uncaught (in promise): TypeError: Cannot read properties of undefined (reading '1')

Any help or suggestions would be helpful.