client: optimize/refactor repository path

- Reduces all calls into a single line
- Redefines path as root repository path

client/src/docker/lib/internal/lib_docker.bash

@@ -17,12 +17,14 @@
 # You should have received a copy of the GNU General Public License
 # along with this program. If not, see <https://www.gnu.org/licenses/>.
 
+[ -z "$DOCKER_FINANCE_CLIENT_REPO" ] && exit 1
+
 #
 # "Libraries"
 #
 
 # Utilities (a container library (but container is never exposed to client code))
-source "$(dirname "$(realpath -s $0)")/../container/src/finance/lib/internal/lib_utils.bash" || exit 1
+source "${DOCKER_FINANCE_CLIENT_REPO}/container/src/finance/lib/internal/lib_utils.bash" || exit 1
 
 #
 # Implementation