Provide a command to dump info to help report an issue/bug

[brettcannon]

If you run Help: Report Issue you get a pop-up window filled with system details that get used to pre-populate an issue. It would be great if we could do something similar for the details we have in our issue template by popping open a new tab with Markdown-formatted details.

[brettcannon]

We should use the full power of GitHub-flavoured Markdown and HTML5 as well, e.g. see #1125 and it's collapsible sections thanks to https://developer.mozilla.org/en-US/docs/Web/HTML/Element/details .

[DonJayamanne]

We might want to keep an eye out on the following issue microsoft/vscode#45673

[MikhailArkhipov]

Collection of user env may not be appropriate since we need to observe data collection and retention policies. 'Report issue' command may be suppressed by corporate IT policies and we can't bypass that.

[brettcannon]

This is to generate a Markdown file that people can copy and paste into GitHub, so there's no IT policy that we would be going against unless a web browser is against policy. 😉