Add tray icon context menu for deactivating tunnel

[SVNKoch]

Fixes #19

Change:

• added tray context menu button
  • is disabled when not connected to tunnel
• cleaned up some duplicated code
• disabled notification for when disconnecting when not connected already

[RileyXX]

Nice work! I appreciate this very much. Thank you.

[SVNKoch]

@wiresock I think you forgot to merge the main branch back to the no-uwp branch. In the no-uwp release this tray option doesn't appear

[wiresock]

@SVNKoch Yes, you are correct. This isn't the first time I've forgotten this branch. I've updated the release binaries.