Reject invalid records

[AlexanderAllen]

GPG indicator will happily capture and display any GPG record, regardless if it's revoked or expired.
It would be nice to:

• Change the color of the taskbar area belonging to the extension to "Red" if the extension detects an expired or revoked key.
• GPG already outputs the expiration and validity status, but the extension's regex does not capture any of this information, and therefore cannot display it. A more robust regex and associated TypeScript types will open the door to more possibilities.
• Raise a popup with the existing logging facilities to notify the user of a potential error condition. It's still obviously up to the user to fix his issues with his keys.