Move away from TS and use JSDoc

[achou11]

Considering that this can be consumed by other applications, thinking that it may be worth removing the dependency on TS and sticking to the JSDoc-first approach. Of course can still use declaration files for anything that can't easily be expressed in JSDoc, but given the tooling overhead with Typescript and the relatively non-strict need for it in this project, I'd be interested in moving away from it if possible