Implement 22 default/additive primitives across non-Haskell hosts

[joshsh]

Background

While adding test coverage for previously-untested primitives (#417), the new tests exposed a
pre-existing gap: 22 primitives are defined in the kernel and implemented for the Haskell host,
but have no native implementation on the other 7 hosts (Java, Python, Scala, Clojure, Common Lisp,
Emacs Lisp, Scheme). On origin/main these were untested and unimplemented, so the suite was green; the
#417 tests surfaced the gap. The tests were removed from #417 (to keep it green) and belong here alongside
the implementations.

Primitives to implement

defineWithDefault (12) — these carry a canonical Hydra-term default implementation in the kernel, so
they are likely fixable via a single systemic default-impl-registration wiring per host rather than 12
hand-written impls:

eithers.{apply, compose, pure}, equality.notEqual, functions.{compose, const, flip},
lists.takeWhile, optionals.{foldList, mapList, mapSet}, sets.filter

plain define (10) — these need genuine per-host native implementations:

chars.isDigit, effects.mapSet, lists.{compose, foldList, mapList, mapOptional, mapSet},
maps.{difference, intersection, unions}

Scope

22 primitives × 7 non-Haskell hosts. Before hand-implementing, investigate whether the 12
defineWithDefault primitives share one root cause — the default implementation not being registered into
the non-Haskell host interpreters (cf. #388) — which could resolve all 12 at once per host. Re-add the
corresponding hydra-kernel test cases as each primitive lands.

Acceptance

/test all green with the 22 primitives' test cases restored.

Origin

Surfaced by #417 (Tentatively finalize existing primitives). Pre-existing; not a #417 regression. Split out
so #417's rename/move/removal wave can land and unblock #416.