Remove Deref impls

[dhardy]

Remove Deref, DerefMut impls for all widgets with their own Id. This brings Kas more in-line with the Deref recommendations:

In general, deref traits should not be implemented if:
[..]
the type has methods that are likely to collide with methods on the target type;

There remains some potential for method collisions via Deref on Map and MapAny, but such cases should cause other errors due to the differing data type on the only methods which do not simply forward to the inner method anyway.