refactor(ivy): create Injector interface; remove dependency on Ivy (#28066)

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

packages/core/src/di.ts

@@ -7,20 +7,20 @@
  */
 
 /**
- * @module
- * @description
- * The `di` module provides dependency injection container services.
+ * This file should not be necessary because node resolution should just default to `./di/index`!
+ *
+ * However it does not seem to work and it breaks:
+ *  - //packages/animations/browser/test:test_web_chromium-local
+ *  - //packages/compiler-cli/test:extract_i18n
+ *  - //packages/compiler-cli/test:ngc
+ *  - //packages/compiler-cli/test:perform_watch
+ *  - //packages/compiler-cli/test/diagnostics:check_types
+ *  - //packages/compiler-cli/test/transformers:test
+ *  - //packages/compiler/test:test
+ *  - //tools/public_api_guard:core_api
+ *
+ * Remove this file once the above is solved or wait until `ngc` is deleted and then it should be
+ * safe to delete this file.
  */
 
-export * from './di/metadata';
-export {InjectableType, InjectorType, defineInjectable, defineInjector} from './di/interface/defs';
-export {forwardRef, resolveForwardRef, ForwardRefFn} from './di/forward_ref';
-export {Injectable, InjectableDecorator, InjectableProvider} from './di/injectable';
-export {INJECTOR, Injector} from './di/injector';
-export {inject, InjectFlags} from './di/injector_compatibility';
-export {ReflectiveInjector} from './di/reflective_injector';
-export {StaticProvider, ValueProvider, ConstructorSansProvider, ExistingProvider, FactoryProvider, Provider, TypeProvider, ClassProvider} from './di/interface/provider';
-export {createInjector} from './di/r3_injector';
-export {ResolvedReflectiveFactory, ResolvedReflectiveProvider} from './di/reflective_provider';
-export {ReflectiveKey} from './di/reflective_key';
-export {InjectionToken} from './di/injection_token';
+export * from './di/index';