create test-skeleton folder on user creation

[individual-it]

creating a user with a skeleton folder is not implemented, so tests that expect a skeleton folder to exist fail, to fix that we need ether to rewrite all tests that use the skeleton folder or create one e.g. by coping the files to the known location

[PVince81]

the skeleton feature in OCIS is not planned for the MVP milestone but will likely come later on.

for the affected tests, I suggest to rewrite them, at least for the ones expecting only few entries
I suggest we start with #14 so we get unblocked there

[individual-it]

@PVince81 @haribhandari07 is in the process to fix the test-infrastructure so it will emulate the skeleton feature, simply by copying the files (no need to implement it in OCIS)
We are doing the same in the UI tests in phoenix when running with ocis

[PVince81]

@individual-it is there a WIP PR for visibility ?

[individual-it]

owncloud/core#37363