This change supports compilation of components, directives, and modules
within ngtsc. Support is not complete, but is enough to compile and test
//packages/core/test/bundling/todo in full AOT mode. Code size benefits
are not yet achieved as //packages/core itself does not get compiled, and
some decorators (e.g. @Input) are not stripped, leading to unwanted code
being retained by the tree-shaker. This will be improved in future commits.
PR Close#24427
Ivy definition looks something like this:
```
class MyService {
static ngInjectableDef = defineInjectable({
…
});
}
```
Here the argument to `defineInjectable` is well known public contract which needs
to be honored in backward compatible way between versions. The type of the
return value of `defineInjectable` on the other hand is private and can change
shape drastically between versions without effecting backwards compatibility of
libraries publish to NPM. To our users it is effectively an `OpaqueToken`.
By prefixing the type with `ɵ` we are communicating the the outside world that
the value is not public API and is subject to change without backward compatibility.
PR Close#23371
Alex Rickabaugh
Kara Erickson
Igor Minar
Miško Hevery
Victor Berchet
Jason Aden