fix(doc): add some docs for kv dataformat, and expose internal commands

fix(expose): expose kv serializer to public

feat(dataformat): add key-value format

feat: restructred json/csv into common DateFormat type

makes it easier to generalize other future features over different dataformats

BREAKING CHANGE: exports in package has changed

fix(api): better typings and api, and added some documentation

build(publish): publish package as publish