add customization option to open note file of current session after kill session

[yanghaoxie]

If we visit other buffers during we reading a org-noter session, the most recent buffer we visited will be open after we execute org-noter-kill-session.

However, in some situations, we want to visit the note file even after kill session.

This pull request add a customization option to always open note file after org-noter-kill-session.

[weirdNox]

Hi there! Thanks for your contribution!
One thing: there are several ways of killing a session, one of which is killing the notes buffer. So, I think this probably should have 3 different possible settings,

• nil doesn't do anything
• ressurect always opens the file even if it was killed
• all other non-nil switches to the file if it is open