LU-11083 tests: automatically load external modules

LU-11083 tests: automatically load external modules

In the test-framework function load_module(), try to load (using
modprobe) any not yet loaded modules (which are assumed to be
external) that the current module depends on.

Test-Parameters: trivial

Signed-off-by: John L. Hammond <jhammond@whamcloud.com>
Change-Id: Id1d10519b00854600d095b861670e96f906298fc
Reviewed-on: https://review.whamcloud.com/32790
Tested-by: Jenkins
Reviewed-by: Quentin Bouget <quentin.bouget@cea.fr>
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Jian Yu <yujian@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>