add new setup for running common tests that mimics sqlfs_op_* functions

The sqlfs_op_* functions are the versions that are handed to libfuse.
They handle tracking the sqlfs using pthread_key_t.
don't run tests by default that require root/fuse access
support multi-threaded operation with sqlsf_init_key() and fixed get_sqlfs()

In multi-threaded operation, we don't get the sqlfs_t using sqlfs_open().
Instead, get_sqlfs() generates it and stores it based on when its needed.
add new setup for running common tests in multi-threaded style with a key