This change is a prerequasity for a later change which will turn the
'di' into its own bazel package. In order to do that we have to:
- have `Injector` type be importable by Ivy. This means that we need
to create `Injector` as a pure type in `interface` folder which is
already a bazel package which Ivy can depend on.
- Remove the dependency of `class Injector` on Ivy so that it can be
compiled in isolation. We do that by using `-1` as special value for
`__NG_ELEMENT_ID__` which tells the Ivy `NodeInjector` than
`Injector` is being requested.
PR Close#28066