Alpha - subject to change.
Returns truthy iff Nippy *appears* to support freezing the given argument.

`:allow-clojure-reader?` and `:allow-java-serializable?` options may be
used to enable the relevant roundtrip fallback test(s). These tests are
only **moderately reliable** since they're cached by arg type and don't
test for pre/post serialization value equality (there's no good general
way of doing so).