Primeng: Feat(ng-packagr): use ng-packagr to build library

[leo6104]

I'm submitting a ... (check one with "x")

[ ] bug report => Search github for a similar issue or PR before submitting
[x] feature request => Please check if request is not on the roadmap already https://github.com/primefaces/primeng/wiki/Roadmap
[ ] support request => Please do not submit support request here, instead see http://forum.primefaces.org/viewforum.php?f=35

Current behavior

primeng use gulp & ts compile for angular library build. But Angular recommend ng-packagr as library build system.

Expected behavior

Please change primeng build system to ng-packagr build. It will make primeng compatible with Angular Ivy compile.

[cagataycivici]

PrimeNG 9 uses ng-packagr.