Built-in codec for MapSet.t() and MapSet.t(elem).
Encodes MapSet structs to JSON arrays and decodes JSON arrays back to MapSet.
The resulting JSON array reflects the unordered nature of sets — duplicate
entries that may appear in the decoded list are collapsed.
For MapSet.t(elem), each element is recursively encoded/decoded according to
its type. For MapSet.t(), elements are passed through as-is.
Registration
Registered automatically when the :spectral application starts. To use a
different codec for MapSet.t(), set it in config :spectra, :codecs;
user-configured codecs take precedence over the built-ins.