Add type information for Pylance

[munro]

A lot of the Python plotly library produces red squiggles in VS Code for Pylance.

From my experience, Pylance seems to work the best out of the box versus Pyright or mypy, so that seems to be the best tool focus adding support for.

I think one way is to add support without altering the library is adding type information to https://github.com/python/typeshed — but generally for my libraries I try to make use of the typing & typing-extensions modules as much as I can. Not sure if that's possible for backwards compatibility though, so typeshed may be the way to go. I've yet to add my own type information for an OS library though, so take all this with a grain of salt.

[gvwilson]

Hi - we are trying to tidy up the stale issues and PRs in Plotly's public repositories so that we can focus on things that are still important to our community. Since this one has been sitting for several years, I'm going to close it; if it is still a concern, please add a comment letting us know what recent version of our software you've checked it with so that I can reopen it and add it to our backlog. Thanks for your help - @gvwilson