Don't save to history from 'eshell-command' when aborting

Don't save to history from 'eshell-command' when aborting

* lisp/eshell/eshell.el (eshell-add-input-to-history)
(eshell--save-history): Declare.
(eshell-command-mode-exit): New function...
(eshell-command-mode): ... use it.

* lisp/eshell/em-hist.el (eshell-hist-initialize): Don't handle
minibuffer logic here.  Always read history file (this ensures that
'eshell-command' can see the history, too).
(eshell-add-command-to-history): Remove.

(cherry picked from commit 3407e274999ce80582932332b108d84fba69d107)