Support multi-line prompt and contents in previous-line-or-history-element.

Support multi-line prompt and contents in previous-line-or-history-element.

* lisp/simple.el (previous-line-or-history-element): Move to the
beginning of minibuffer contents if there is editable minibuffer contents
on the same line after moving point to the prompt (bug#46033).
Fix minimal old-column from 0 to 1 to put point at the beginning of
minibuffer contents after going to the previous history element.