tests: unittest: Add new test for hal_common_get_backend and put_backend function

tests: unittest: Add new test for hal_common_get_backend and put_backend function

hal_common_get_backend and hal_common_put_backend functions are very
important because they are in charge of loading/unloading the hal
backend library for all hal backends and also verify the validation checking
of the loaded hal backend library. When executing hal_common_get_backend and
hal_common_put_backend, there are very complex validation sequence.

It means that have to verify the internal logic of both
hal_common_get_backend and hal_common_put_backend at the implementation
step in order to catch the error.

So that add new test for hal_common_get_backend and
hal_common_put_backend functions.

Change-Id: I8d42e9327248c283d8f01fc8b5f5926e0d371ba5
Signed-off-by: Chanwoo Choi <cw00.choi@samsung.com>