github: update issue templates

[wchargin]

Summary:
This commit adds issue templates for bug reports, feature requests, and
installation problems, with specific instructions for each.

This also resolves the nag from GitHub to move to the new issue template
workflow.

I created these by following the “issue template wizard” described here:
https://help.github.com/en/articles/creating-issue-templates-for-your-repository

Test Plan:
I’ve committed this to the default branch of my fork. Try drafting an
issue there: https://github.com/wchargin/tensorboard/issues/.

wchargin-branch: github-issue-templates

[wchargin]

Addressed. You’re mostly right, I think. I’ve offloaded most of the
environment work to diagnose_tensorboard.py (#2237), and made the
“steps to reproduce” wordings more lenient.

[nfelt]

In general I think this is an improvement, but it feels a little heavyweight to ask users to download a script to collect data even if tensorboard mostly works rather than just building that functionality into TensorBoard itself. (For installation problems, of course, that's the best we can do.)

Maybe we could put this script in the pip package somewhere and just add a tensorboard --diagnose option that invokes it? That way it seems a little less annoying for the user.

Edited to add: ok, so a downside is that they wouldn't get the latest version of the diagnose script. I guess that might be a good reason to stick with this approach, though I still wish we could smooth it out a little.

[wchargin]

Edited to add: ok, so a downside is that they wouldn't get the latest
version of the diagnose script.

Right, that was my thinking. It’d be a one-line change to setup.py if
we wanted to provide a diagnose_tensorboard binary, but we couldn’t
keep that up to date with checks and suggestions.

I’ll merge this PR as is, and would be happy to consider further
improvements to the delivery.