runtime(ftplugin): Use "*" browsefilter pattern to match "All Files"

Problem:  The "*.*" browsefilter pattern only matches all files on
	  Windows (Daryl Lee)
Solution: Use "*" to filter on all platforms but keep "*.*" as the label
	  text on Windows. (Fixes #12685, Doug Kearns)

The *.* browsefilter pattern used to match "All Files" on Windows is a
legacy of the DOS 8.3 filename wildcard matching algorithm.  For reasons
of backward compatibility this still works on Windows to match all
files, even those without an extension.

However, this pattern only matches filenames containing a dot on other
platforms.  This often makes files without an extension difficult to
access from the file dialog, e.g., "Makefile"

On Windows it is still standard practice to use "*.*" for the filter
label so ftplugins should use "All Files (*.*)" on Windows and "All
Files (*)" on other platforms.  This matches Vim's default browsefilter
values.

This commit also normalises the browsefilter conditional test to check
for the Win32 and GTK GUI features and an unset b:browsefilter.

closes: #12759

Signed-off-by: Doug Kearns <dougkearns@gmail.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>
diff --git a/runtime/doc/editing.txt b/runtime/doc/editing.txt
index 2ea6839..d0f8938 100644
--- a/runtime/doc/editing.txt
+++ b/runtime/doc/editing.txt
@@ -1,4 +1,4 @@
-*editing.txt*   For Vim version 9.1.  Last change: 2023 Sep 27
+*editing.txt*   For Vim version 9.1.  Last change: 2024 Jan 14
 
 
 		  VIM REFERENCE MANUAL    by Bram Moolenaar
@@ -1329,8 +1329,9 @@
 filetype plugin, so that the browse dialog would contain entries related to
 the type of file you are currently editing.  Disadvantage: This makes it
 difficult to start editing a file of a different type.  To overcome this, you
-may want to add "All Files\t*.*\n" as the final filter, so that the user can
-still access any desired file.
+may want to add "All Files (*.*)\t*\n" as the final filter on Windows or "All
+Files (*)\t*\n" on other platforms, so that the user can still access any
+desired file.
 
 To avoid setting browsefilter when Vim does not actually support it, you can
 use has("browsefilter"): >