tests/util/grub-shell: Create run.sh in working directory for easily running test...

tests/util/grub-shell: Create run.sh in working directory for easily running test again

Now it becomes trivial to re-run a test from the output in its working
directory. This also makes it easy to send a reproducible failing test to
the mailing list. This has allowed a refactor so that the duplicated code
to call QEMU has be condensed (e.g. the use of timeout and file descriptor
redirection). The run.sh script will pass any arguments given to QEMU.
This allows QEMU to be easily started in a state ready for GDB to be
attached.

Signed-off-by: Glenn Washburn <development@efficientek.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>