Adopt GitHub Auth provider for issues reporter

[RMacfarlane]

Since we now have a way for users to login to GitHub within VSCode, we can leverage this in the issue reporter. As a first step, if the user is already signed in and we have a token with scopes for creating an issue, we can just directly post the issue instead of showing the intermediate "new issue" page

[wolf99]

Point to note: users may have one set of credentials that they work against, but may want to report issues under a different set of credentials. (e.g. work vs personal).