s4:torture/smb2: add smb2_create_simple_file() and torture_setup_simple_file()

s4:torture/smb2: add smb2_create_simple_file() and torture_setup_simple_file()

Instead of the *_complex_file() versions these don't use EA's nor
complex timestamps.

A lot of tests currently using *_complex_file() only fail because
smbd doesn't implement the correct 'change_time' update behavior.
That should not be the reason why all smb2 related tests fail.

Timestamps should be tested in dedicated tests.

BUG: https://bugzilla.samba.org/show_bug.cgi?id=13864

Signed-off-by: Stefan Metzmacher <metze@samba.org>
Reviewed-by: Jeremy Allison <jra@samba.org>