SIL: Ignore AEIC on package declaration inside declarations without effective public access
Quoting Slava:
"The AST-level access is allowed to be 'more public'. I honestly don't
know why, but it's always worked this way and the 'lowered' access
levels must always intersect the access levels of the parents but with
@uic, @aeic and @inlinable, that means just ignoring those attributes if
some enclosing context is not @uic"
rdar://128270848