Enable ivy support and remove ViewEngine support

[pavankjadda]

Angular deprecated ViewEngine in v12 and will be removed in future. I tried to drop ViewEngine support in the past but reverted those changes since it broke existing applications that do not use Ivy

Starting from v13, we can drop support for ViewEngine and Enable ivy. Anybody who uses pre-ivy version of angular can continue to use v12. I created branch 12.x.x to maintain v12 code. Any critical and important fixes found in v13 or later can be back ported to v12 if needed.

And projects that use ivy compatible Angular version can use v13 or later.

[pavankjadda]

@stevermeister we should also add this to our next call.

[pavankjadda]

In todays (2021-10-20) call, it was decided that, we will maintain 2 versions of the library

• 12.x.x(compatible with ViewEngine)
• 13.x.x or later (Ivy compatible and does not support View Engine)

we will back port necessary changes from 13.x.x or later to 12.x.x if needed.

[pavankjadda]

v13 implemented this