org-babel-import-elisp-from-file: Fix detecting delimiter in single-line data

* lisp/org-table.el (org-table-convert-region): When detecting
delimiter in, do not unconditionally fall back to CSV parser.  Only do
it when the line contains commas and use a simple single tab/space
split otherwise.  Add new special delimeter-detection strategy when
SEPARATOR is 'babel-auto - convert to | full line | table instead of
falling back to tab/space split when the region contains a single
line.
* lisp/ob-core.el (org-babel-import-elisp-from-file): Force special
strategy when converting data to lisp.

The commit fixes the problem with first `re-search-forward' in the
`cond' moving point to end of the region, making the third `cond'
branch never match.

A special strategy specific to babel is necessary to preserve the
historic behavior with lines like
: single line with spaces
being converted to a single table cell
: | single line with space |

Reported-by: Matt <matt@excalamus.com>
Link: https://orgmode.org/list/18f24d87b62.d55e94e24743657.3252620114689708448@excalamus.com

lisp/ob-core.el

@@ -3389,7 +3389,9 @@ SEPARATOR is passed to `org-table-convert-region', which see."
 		   ;; If the file was empty, don't bother trying to
 		   ;; convert the table.
 		   (when (> pmax 1)
-		     (org-table-convert-region (point-min) pmax separator)
+		     (org-table-convert-region
+                      (point-min) pmax
+                      (or separator 'babel-auto))
 		     (delq nil
 			   (mapcar (lambda (row)
 				     (and (not (eq row 'hline))

lisp/org-table.el

@@ -892,7 +892,10 @@ nil      When nil, the command tries to be smart and figure out the
          separator in the following way:
          - when each line contains a TAB, assume TAB-separated material
          - when each line contains a comma, assume CSV material
-         - else, assume one or more SPACE characters as separator."
+         - else, assume one or more SPACE characters as separator.
+`babel-auto'
+       Use the same rules as nil, but do not try any separator when
+       the region contains a single line and has no commas or tabs."
   (interactive "r\nP")
   (let* ((beg (min beg0 end0))
 	 (end (max beg0 end0))
@@ -909,12 +912,15 @@ nil      When nil, the command tries to be smart and figure out the
     (if (bolp) (backward-char 1) (end-of-line 1))
     (setq end (point-marker))
     ;; Get the right field separator
-    (unless separator
+    (when (or (not separator) (eq separator 'babel-auto))
       (goto-char beg)
       (setq separator
 	    (cond
-	     ((not (re-search-forward "^[^\n\t]+$" end t)) '(16))
-	     ((not (re-search-forward "^[^\n,]+$" end t)) '(4))
+	     ((not (save-excursion (re-search-forward "^[^\n\t]+$" end t))) '(16))
+	     ((not (save-excursion (re-search-forward "^[^\n,]+$" end t))) '(4))
+             ((and (eq separator 'babel-auto)
+                   (= 1 (count-lines beg end)))
+              (rx unmatchable))
 	     (t 1))))
     (goto-char beg)
     (if (equal separator '(4))