[Pythonclient] Add missing docstrings

[Rajat Singhal (rajat2004)]

WIP

[Rajat Singhal (rajat2004)]

As a side note, many PR's Travis status are not being updated, might be due to https://travis-ci.community/t/github-status-not-posted-on-commits-on-repositories-using-legacy-service-integration/7798

[Rajat Singhal (rajat2004)]

Also, would be great to have a proper list of APIs auto-generated and added to the Wiki, that'll make things much easier. What should be used for that, Sphinx, pdoc, or something else?

[Ratnesh Madaan (madratman)]

I've added a first version of sphynx doc generator. I'll do the next step soon: call build_api_docs.sh from build_docs.sh; copy sphynx html to gh-pages and rename it to api.html; and then finally we need a little button on main github.io site to link to API / or add it to the readme

[Rajat Singhal (rajat2004)]

Need to add docstring for all the APIs to make it appear on the list, which is quite painful 😅
Also fixing the types of the params will be good to make it jump to the type definition

Well, just add undoc-members and voila!

One final thing which would be very useful is to automate the entire doc build, rather than require a manual update. Having outdated and conflicting info causes issues, and manual update each small change in a PR takes up valuable time of the maintainers

[Rajat Singhal (rajat2004)]

I've made a new PR #2599 while has some fixes noticed while working on this PR
Wanted to keep this one just for docs and not include other fixes which make things difficult while reviewing

Only some MoveBy APIs remaining. Note that I haven't personally tested all the APIs