Add support for Angular 16

[RuthraKoutham]

I am facing the below issue using Angular 16 with ng2-tree version 2.0.0-rc.11.
Also I can see the pull request for this #353.
It will be helpful if the new version got released with this PR, compatible for angular 16 and above.

Issue:
This likely means that the library (ng2-tree) which declares TreeModule is not compatible with Angular Ivy. Check if a newer version of the library is available, and update if so. Also consider checking with the library's authors to see if the library is expected to be compatible with Ivy.