The `SCHEDULER` provider was used previously when both ViewEngine and Ivy code was present. After some prior refactoring, all references to the `SCHEDULER` token were removed, but the token itself remains present in the `ApplicationModule`, which makes it non-tree-shakable.

This commit removes the `SCHEDULER` token as unused.

…tus` tree-shakable

The `Compiler`, `ApplicationRef` and `ApplicationInitStatus` classes are registered as non-tree-shakable providers in the `ApplicationModule`. This commit converts them to the tree-shakable providers instead.

…` tree-shakable

The `ApplicationModule` module has a number of tokens declared as non-tree-shakable providers. This commit updates them to make tree-shakable.