Forbid annotations on class extends and implements clauses

[Ao-senXiong]

We should issue error if there is annotation on extends and implements clauses instead of check the subtype like suggested in the comment

checker-framework/framework/src/main/java/org/checkerframework/common/basetype/BaseTypeVisitor.java

Line 831 in 064d327

// If "@B class Y extends @A X {}", then enforce that @B must be a subtype of @A.

.

That is @Q class B extends A{} is valid and subtype check of qualifier is for @Q <: bound(A), while @Q class B extends @P A{} is not valid.

[wmdietl]

What is valid or not will depend on the type system, but for most type systems the current rules are too lenient.
The Nullness Checker raises nullness.on.supertype for annotations in extends/super and we should generalize this as the default behavior.
A type system that needs annotations in that location should still be able to override checkExtendsAndImplements.

(The comment about the current behavior should be moved from BaseTypeVistitor to the javadoc of checkExtendsAndImplements and then adapted to the new behavior.)