org-keys: Bind ESC <left> by default
* lisp/org-keys.el (org-mode-map): Bind `org-metaleft' to ESC <left>
by default, not just in terminals. This completes the ESC <arrow>
binding group. ESC <right>, <up>, and <down> are already bound and
missing ESC <left> can be confusing.
Reported in https://orgmode.org/list/Yf6lsTR3JSNSXRDX@x.local