Harpoon 2 needs terminal config

[ThePrimeagen]

I don't use terminals but i would love to see a terminal attempt.

it would require some interesting changes where selecting through a list with an empty slot should create a terminal.

1. likely a list setting that needs to be thought of
2. a new config for terminals

[ThePrimeagen]

this commit adds select with nil which is a requirement of terminal harpooning

https://github.com/ThePrimeagen/harpoon/commit/8dd3d909fd46cef5abb49ef52558420e691524a2