Generate queue .data files according to custom command size (#2375)

Small edits to `gen_test_data.sh` to generate `.data` files with
argument-specified lengths of commands, and a specified output
directory. If no arguments are provided, the size and the output
directory are set to the default (20000 and `<SCRIPT_DIR>/../tests`).
It's a bit hacky, but since I only need it for profiler debugging
purposes, I hope it's ok?

frontends/queues/test_data_gen/gen_test_data.sh

@@ -1,9 +1,17 @@
 #!/usr/bin/bash
 
-num_cmds=20000
+if [[ $# -eq 2 ]]; then # Generate custom-length command list to the specified output directory
+    num_cmds=$1
+    tests_dir=$2
+    mkdir -p ${tests_dir}/binheap/round_robin ${tests_dir}/binheap/strict ${tests_dir}/round_robin ${tests_dir}/strict # NOTE: hacky and will break when other tests are created.
+    echo "Number of commands: ${num_cmds}; output directory: ${tests_dir}"
+else
+    num_cmds=20000
+    tests_dir="$(dirname "$0")/../tests"
+fi
+
 queue_size=16
 
-tests_dir="$(dirname "$0")/../tests"
 data_gen_dir="$(dirname "$0")"