fix(E605): add missing test files for tcf, tcpcl, tls, tm, tomlt
Create test_<module>.ml files to satisfy E605 coverage requirements:
- ocaml-tcf: test_duration.ml, test_tcf.ml with roundtrip tests
- ocaml-tcpcl: rename test.ml → test_tcpcl.ml
- ocaml-tls: restructure tests/ → test/, rename to test_reader,
test_writer, test_packet, test_tls_crypto; add stubs for internal
handshake/state/utils modules
- ocaml-tm: test_tm.ml with encode/decode tests
- ocaml-tomlt: test_toml.ml (renamed from test_tomlt), test_toml_error