When type-checking a component, the declaring NgModule scope is used
to create a directive matcher that contains flattened directive metadata,
i.e. the metadata of a directive and its base classes. This computation
is done for all components, whereas the type-check scope is constant per
NgModule. Additionally, the flattening of metadata is constant per
directive instance so doesn't necessarily have to be recomputed for
each component.
This commit introduces a `TypeCheckScopes` class that is responsible
for flattening directives and computing the scope per NgModule. It
caches the computed results as appropriate to avoid repeated computation.
PR Close#38539
ba95b79a21