Support different "closed as" types for issues

[smichel17]

Somewhat recently, GitHub added the ability to close an issue either as "completed (Done, closed, fixed, resolved)" or "not planned (Won't fix, can't repro, duplicate, stale)".

Closing from the app currently defaults to "as completed". It would be nice to be able to close as not planned.

Todo:

• Check if there is api support
• Figure out a UI (probably the biggest task)
• Implement it (might be more or less work depending on the design)

[maniac103]

See #1223 ;-)

[smichel17]

Ha— I searched issues but not PRs!