As a hack to get the Ivy compiler ngtsc off the ground, the existing
'allowEmptyCodegenFiles' option was used to control generation of ngfactory
and ngsummary shims during compilation. This option was selected since it's
enabled in google3 but never enabled in external projects.
As ngtsc is now mature and the role shims play in compilation is now better
understood across the ecosystem, this commit introduces two new compiler
options to control shim generation:
* generateNgFactoryShims controls the generation of .ngfactory shims.
* generateNgSummaryShims controls the generation of .ngsummary shims.
The 'allowEmptyCodegenFiles' option is still honored if either of the above
flags are not set explicitly.
PR Close#33256
d4db746898