*: add missing :with-test alcotest deps; broaden lint workspace check

Two changes squashed because they uncovered each other:

1. Sweep [(alcotest :with-test)] into 18 packages whose tests use
alcotest but didn't declare it in opam. Each verified by build +
runtest. Affected: ocaml-adm, ocaml-aem, ocaml-agent, ocaml-cdm,
ocaml-conpool, ocaml-coordinate, ocaml-csv, ocaml-demod, ocaml-dsp,
ocaml-flexacm, ocaml-globe, ocaml-kepler, ocaml-kvn, ocaml-rdm,
ocaml-respond, ocaml-spacedata, ocaml-stix, ocaml-vec3, osrelease.

2. [monopam lint] now treats every workspace-local library name as
workspace-internal, not just the ones with no [(public_name ...)].

Before, [local_private_libs] called [Dune.File.private_library_names]
which only returned [(library (name X))] stanzas WITHOUT a public
name. So a [(library (name cookie_jar) (public_name nox-cookie.jar))]
was treated as external -- a sibling [(test (libraries cookie_jar))]
triggered a [Missing_test] for a non-existent opam package
[cookie_jar].

Switch to [Dune.File.library_names] (every internal name) and rename
the helper to [local_library_names]. A workspace-local
[(libraries X)] now resolves to the workspace artifact regardless of
whether [X] also has a public_name; opam-package matching only
applies to truly-external library refs.

Cleared a swathe of false-positive missing-test reports for
subtrees that internally dot-name their sub-libraries (irmin's
irmin_admin/irmin_cbor/..., ocaml-cookie's cookie_jar, ocaml-claude-
skills's skills, etc.).