data.priority-map: deftype interop fixes (rseq, arity-overload, empty, Sorted)

data.priority-map's whole suite passes (4/4). It leans on deftype/collection
interop jolt got wrong; four general fixes:

- rseq dispatches to a deftype's clojure.lang.Reversible.rseq method instead of
  always demanding a vector/sorted-coll (natives-seq.ss).
- a deftype method declared at two arities from two interfaces now dispatches by
  arity: the priority-map has seq[this] (Seqable) and seq[this ascending]
  (Sorted), so (.seq pm false) must reach the 2-arg one. find-method-any-protocol
  now matches the call's arg count via procedure-arity-mask, and a deftype's own
  declared method wins over the generic collection interop in dot-forms.
- (empty x) on a deftype/record with its own empty method uses it rather than
  returning {} (jolt.host/jrec-method? gate in clojure.core/empty).
- clojure.lang.Sorted (comparator / entryKey / seqFrom) works on jolt's
  sorted-map/set, so subseq/rsubseq run — including the priority-map delegating
  .comparator to its backing sorted-map (dot-forms.ss + host-static.ss).

Listed in docs/libraries.md + the site. One re-mint (clojure.core/empty);
everything else runtime. make test green (0 new divergences), shakesmoke
byte-identical.

docs/libraries.md

@@ -63,6 +63,8 @@ e.g. the [ring-app example](https://github.com/jolt-lang/examples/tree/main/ring
 * [data.csv](https://github.com/clojure/data.csv) — reading and writing CSV.
 * [data.codec](https://github.com/clojure/data.codec) — base64 encode/decode over
   byte arrays.
+* [data.priority-map](https://github.com/clojure/data.priority-map) — priority
+  maps (incl. keyfn / custom comparator), with `subseq`/`rsubseq`.
 * [test.check](https://github.com/clojure/test.check) — property-based testing
   (generators, `quick-check`, shrinking).
 * [tick](https://github.com/juxt/tick) — date/time over Jolt's `java.time`;