Fix "make check"

Various fixes to the test suite:

 1. test-xbmc wasn't building due to a double-definition of main () because main.a was in DIRECTORY_ARCHIVES. It's already in MAINOBJS so I just removed it from the former.
 2. ActionCreateFolder/ActionDeleteFolder expect the destination to be the *parent* directory and not the directory to be created / destroyed
 3. Ensure that CAdvancedSettings is reset between test runs as it can be polluted between tests and cause nondeterministic failures.
 4. Refactor TestFileItem.cpp: use Google Test's parameterized test driver as opposed to iterating within the test body so that we can see specifically where failure is occurring.

Note: make check is still segfaulting on environment teardown. Fixing that would require a deeper dive into the global instances of CLog and friends which looks like a deep rabbit hole that's not worth getting into right now.