patch 9.0.1972: win32: missing '**' expansion test

Problem:  win32: missing '**' expansion test (after v9.0.1947)
Solution: Add test for MS-Windows

win32: Add "**" test

Vim supports "**" on MS-Windows. However, it is not tested by
`Test_glob_extended_bash`.

Unlike Unix, it doesn't use 'shell' and doesn't support {,} expansion.
So, I added as a separate test.

related: #13205
closes: #13250

Signed-off-by: Christian Brabandt <cb@256bit.org>
Co-authored-by: Ken Takata <kentkt@csc.jp>
diff --git a/runtime/doc/editing.txt b/runtime/doc/editing.txt
index a015c84..a9c81f4 100644
--- a/runtime/doc/editing.txt
+++ b/runtime/doc/editing.txt
@@ -386,8 +386,8 @@
 
 					*starstar-wildcard*
 Expanding "**" is possible on Unix, Win32, macOS and a few other systems (but
-it may depend on your 'shell' setting. It's known to work correctly for zsh; for
-bash this requires at least bash version >= 4.X).
+it may depend on your 'shell' setting on Unix and macOS. It's known to work
+correctly for zsh; for bash this requires at least bash version >= 4.X).
 This allows searching a directory tree.  This goes up to 100 directories deep.
 Note there are some commands where this works slightly differently, see
 |file-searching|.