Adds a reference to the ts_ member, for use by BPF class to access the
storage object and perform lookups.

Note that get_hash_table/get_stack_table don't have an error return, so
failure to lookup the table name will result in undefined behavior
(which is actually the case prior to this commit as well).

Also update indentation per clang-format
Signed-off-by: Brenden Blanco <bblanco@gmail.com>