Create issue from markdown template

[Balastrong]

I was wondering why #1792 is still open so I tried to create a proof of concept for that.

At the current state I can read from {docs,.github}/ISSUE_TEMPLATE/*.md and put the files to the quick pick to get selected by the user.
If a file is selected I read the content and roughly parse title and body to pass them to makeNewIssueFile, otherwise the existing default file is opened.

template.mov

If it's something worth working on I'll be happy to put some more effort in either in this PR of in future ones, for example:

• Add a "blank" option to the quick pick
• Improve the parsing logic
• Parse more fields from the metadata
• Display the template name instead of the file name on the quick pick
• Add support for yaml issue forms

[alexr00]

@Balastrong, I'd be happy to take a PR for this, thank you! #1792 it has not been high enough priority to work on, and a PR will solve that. What you have looks like a good start, but I do think some of your bullet points are needed, specifically "blank" and template name, before this feature is ready.

[Balastrong]

Thank you @alexr00! I'll work on that :)

[Balastrong]

I added the two features :)

You can now find a "Blank issue" option at the end of the list and you will also get the blank template if you press Esc.
Issue names are now displayed in the list (I also added the description as it came basically for free)

demo2.mov

[alexr00]

Looks good, thank you! I restored the behavior where you don't have to chose a repo if the active file belongs to a repo and made a few style changes.