Type.AssignableTo panics with "reflect: unimplemented: AssignableTo with interface"

[fxamacker]

Some packages like fxamacker/cbor require Type.AssignableTo to support Interface.

There was some prior discussion at fxamacker/cbor#295 (comment).

Projects using packages that require Interface support can encounter panics from the following code.

tinygo/src/reflect/type.go

Lines 956 to 969 in 6384eca

	func (t *rawType) AssignableTo(u Type) bool {
	if t == u.(*rawType) {
	return true
	}
	if u.Kind() == Interface && u.NumMethod() == 0 {
	return true
	}
	if u.Kind() == Interface {
	panic("reflect: unimplemented: AssignableTo with interface")
	}
	return false
	}

If a solution becomes available, I can use some existing tests in fxamacker/cbor to help test it.