Change annotations propagation to consider transitive owners

[mario-bucev]

Before this PR, all annotations from the direct owner of a symbol were applied to that symbol. For instance, a @library object containing a function f would (correctly) get the @library flag, but not any of its inner functions (which is an incorrect behavior). Furthermore, a function annotated with @opaque (incorrectly?) propagates this annotation to its direct inner functions.

This PR changes the following:

• Only the following annotations are propagated to the "children" of a symbol: stainless.annotation.ignore stainless.annotation.library stainless.annotation.extern stainless.annotation.dropVCs stainless.annotation.pure stainless.annotation.wrapping stainless.annotation.keep stainless.annotation.keepFor stainless.annotation.cCode.drop
• These annotations are transitively propagated

[vkuncak]

I do not understand where transitivity is implemented. Not in the diff as far as I can tell, so it was there already but not consistently so?

[mario-bucev]

Before this PR, we only checked for the annotation of the direct owner (sym.owner), now we consider all transitive owners using sym.ownersIterator.drop(1) (where we drop the first element because ownersIterator returns the sym itself as first element).