Rename --nul-output to --raw-output0, abort on string containing NUL

The option naming --nul-output was confusing, especially when we have a
similar option for input stream in the future (--nul-input vs --null-input).
Based on the observation of other command line tools, we rename the option
to --raw-output0. We also drop the short option -0 to avoid confusion on
introducing the NUL-delimited input option.

Unlike the other command line tools outputting file names with NUL delimiter,
jq deals with JSON, and its strings may contain NUL character. To protect
users from the risk of injection attacks, we abort the program and print an
error message before outputting strings including NUL character. Closes #2683.

tests/shtest

@@ -165,12 +165,20 @@ cmp $d/out $d/expected
 printf "[1,2][3,4]\n" | $JQ -cs add > $d/out 2>&1
 cmp $d/out $d/expected
 
-# Regression test for -0 / --nul-output
+# Regression test for --raw-output0
 printf "a\0b\0" > $d/expected
-printf '["a", "b"]' | $JQ -0 .[] > $d/out 2>&1
-cmp $d/out $d/expected
-printf '["a", "b"]' | $JQ --nul-output .[] > $d/out 2>&1
+printf '["a", "b"]' | $VALGRIND $Q $JQ --raw-output0 .[] > $d/out
 cmp $d/out $d/expected
+printf "a\0" > $d/expected
+if printf '["a", "c\\u0000d", "b"]' | $VALGRIND $Q $JQ --raw-output0 .[] > $d/out; then
+  echo "Should exit error on string containing NUL with --raw-output0" 1>&2
+  exit 1
+elif [ $? -ne 5 ]; then
+  echo "Invalid error code" 1>&2
+  exit 1
+else
+  cmp $d/out $d/expected
+fi
 
 ## Test streaming parser