Update feedback system to new github issues format

[adegeo]

Summary

@homing1 please review the docfx file. I copied the settings from the dotnet/docs repo, from a PR you contributed to.

[homing1]

@adegeo The metadata properties look good to me, but I don't have feedback on their values as I don't know what values are appropriate for this repo. open_source_feedback_issueTitle is optional. You can leave it as is, or you can omit it if you don't want a default title for the issue form.

You can preview it with this link: https://review.learn.microsoft.com/en-us/dotnet/desktop/winforms/whats-new/net70?view=netdesktop-7.0&branch=pr-en-us-1711

The Open a documentation issue link won't work properly until the issue template that you're adding in this PR is merged.

[adegeo]

Thanks @homing1