Tests: expose 'args' passed to hook scripts

- Useful to validate that all the expected arguments were passed with
  correct escaping.
- Update test/template.t with one use-case for 'args'

test/test_hooks/wrapper.sh

@@ -6,7 +6,7 @@ IN="${ORIGINALHOOK}.log.in"
 OUT="${ORIGINALHOOK}.log.out"
 
 # Let it know that we were executed
-echo "% Called at $(python -c 'import time; print(time.time())')" >> ${IN}
+echo "% Called at $(python -c 'import time; print(time.time())') with '$@'" >> ${IN}
 
 # Log what arrives via stdin to ${IN} and what comes via stdout to ${OUT}
 $ORIGINALHOOK "$@" < <(tee -a ${IN}) > >(tee -a ${OUT})