…#1296)

- Move instanceof logic from SA to InstanceofUtil. The new generics check here is questionable as the actual generic geclaration from instanceofThis is never used, and some other LeftHandGenericUse is passed in instead. This could use a revision that is out of scope for this commit.
- Fix SA instanceof `(CClassType, CClassType)` method signature being redirected to the `(Mixed, CClassType)` instanceof method, effectively making all types `ClassType` instead of their actual type.

Co-authored-by: LadyCailin <savannahcailin@gmail.com>

Unit tests fail pretty hard, still needs debugging.

This completes the generics backend, though it will be a while before
the frontend part is ready.

LeftHandSideType is a class that is similar to CClassType, but can
contain left hand side semantics. Particularly, it can contain type
unions, and LHS generic statements. As all CClassTypes are valid LHS
identifiers though, tight coupling has been added to convert from
CClassType to LHS notation easily. In general though, most parts of the
type system work with LHS types now, though future use cases (such as
the new keyword) will specifically work only with CClassTypes. Both the
runtime and the SA framework have been adjusted to use LHS types now
instead.

Also, add back no-env methods in Static for now. These are deprecated,
but will give a phase in period for extensions to adapt, rather than
having a hard break right now, while the underlying thing (user objects)
isn't ready yet anyways.

This reverts commit 48d21b6.