Problem: when close() is triggered from visual or operator-pending
mode (e.g. pressing q after d in an oil buffer), the buffer closes
instead of canceling the pending operation. This happens because
keymaps without an explicit mode default to "" which covers normal,
visual, select, and operator-pending modes.
Solution: check the current mode at the top of close() and send
<Esc> to cancel the mode instead of proceeding with the close. The
check covers all visual modes (v, V, CTRL-V), select modes (s, S,
CTRL-S), and operator-pending submodes (no, nov, noV, noCTRL-V).
Based on: stevearc/oil.nvim#495
