create skeleton files via WebDAV Upload in test when copy is not possible

[individual-it]

when running tests on EOS backend its difficult to copy the skeleton files just into the storage, simple solution: upload them via WebDAV

e.g. when SKELETON_DIR is set but no OCIS_REVA_DATA_ROOT, upload via webDav

see:

core/tests/acceptance/features/bootstrap/Provisioning.php

Line 901 in 890ef6e

if (!$revaRoot) {