ngtsc used to assume that all .d.ts dependencies (that is, third party
packages) were imported via an absolute module path. It turns out this
assumption isn't valid; some build tools allow relative imports of
other compilation units.
In the absolute case, ngtsc assumes (and still does) that all referenced
types are available through the entrypoint from which an @NgModule was
imported. This commit adds support for relative imports, in which case
ngtsc will use relative path resolution to determine the imports.
PR Close#25080
e0c0c44d99