Add opt-in to always prompt for repo for issue creation and add comment to issue file specifying the repo

[mikeseese]

This PR adds a githubIssues.alwaysPromptForNewIssueRepo config variable that defaults to false. When set to true, if the user creates a new issue via the + button in the side panel, the extensions will always prompt the user for a repo to create the issue for instead of using the current open file. Behavior should not change for creating issues from selection/etc that are supposed to be directly contextual.

This PR also adds a comment in the NewIssue.md file telling the user which repo the issue will be created in if it's available:

This PR fixes #2099.

[mikeseese]

@microsoft-github-policy-service agree

[mikeseese]

@alexr00 It got a little more complex, but now origin will contain information to reproduce the correct folder manager and remote by adding a new repo URI scheme.

[rzhao271]

Merge conflict Moving the milestone

[mikeseese]

@rzhao271 @alexr00 Merge conflicts have been resolved. This PR is still waiting for a rereview. Thanks!

[alexr00]

Thanks for your patience on this! I'll look at it next week when we start our annual clean up iteration.

[mikeseese]

Sounds good, thanks!