Implement support for the vim sneak motion from the vim-sneak plugin.
The motion jumps forward or backward to any location specified by two
characters.

The Sneak & SneakBackward operators are bound to 'z' and 'Z' by default
to avoid overwriting the 's' and 'S' default keybindings, similar to the
way the original plugin uses 'z' with operators to avoid conflicts.

Reference:
https://github.com/justinmk/vim-sneak

# Conflicts:
#	crates/vim/src/vim.rs