This commit introduces generateSetClassMetadataCall(), an API in ngtsc
for generating calls to setClassMetadata() for a given declaration. The
reflection API is used to enumerate Angular decorators on the declaration,
which are converted to a format that ReflectionCapabilities can understand.
The reflection metadata is then patched onto the declared type via a call
to setClassMetadata().
This is simply a utility, a future commit invokes this utility for
each DecoratorHandler.
Testing strategy: tests are included which exercise generateSetClassMetadata
in isolation.
PR Close#26860
