Chez Phase 2 (inc T): class native + bare class-token resolution (jolt-13zk)

Bare class names (String, Keyword, File...) evaluate to their JVM
canonical-name string, the same value (class x) returns, so
(= String (class "x")) holds and (defmethod m String ...) keys match a
(class ...) dispatch. New host/chez/host-class.ss ports
eval_resolve.janet's class-canonical-names + core_refs.janet's core-class
(scalar arms; collections/seqs are host-taxonomy-dependent and not class-
compared in the corpus).

The analyzer already resolves these names to clojure.core vars (the seed
ctx interns them via setup-class-ctors), so the back end emits
(var-deref "clojure.core" "String") and a runtime def-var! is all that's
needed -- no analyzer change, Janet path untouched. The class native MUST
land together with token resolution: alone it turns the bare-token corpus
cases (562/564) into divergences (this bit last session).

Parity 2154 -> 2163 (cases 560/562/563/564/2500-2503), 0 new divergences.
New test/chez/_class.janet 19/19.

host/chez/jolt-chez.janet

@@ -22,6 +22,7 @@
            "host/chez/atoms.ss" "host/chez/predicates.ss" "host/chez/regex.ss"
            "host/chez/ns.ss" "host/chez/post-prelude.ss" "host/chez/natives-meta.ss"
            "host/chez/natives-str.ss" "host/chez/records.ss"
+           "host/chez/host-class.ss"
            "host/chez/host-static.ss" "host/chez/dot-forms.ss"
            "src/jolt/clojure/string.clj"]
     (array/push parts (slurp f)))