Add simple benchmark tool

Since `#[bench]` is nightly-only, add a simple binary that can be
modified to test the performance of specific queries as needed.

src/bin/bench.rs

@@ -0,0 +1,22 @@
+fn long_insert_into_values_query(rows: usize) -> String {
+  let mut query = r#"INSERT INTO "table_name" ("one","two","three") VALUES "#.to_owned();
+  for i in 0..rows {
+      query.push_str(&format!("({}, {}, {}),", i, i + 1, i + 2));
+  }
+  query.push_str("(0, 0, 0);");
+  query
+}
+
+extern crate sql_lexer;
+
+fn main() {
+  for rows in [200, 2000, 20000] {
+    println!("Sanitising long_insert_into_values_query with {rows} rows");
+    let query = long_insert_into_values_query(rows);
+    let start = std::time::Instant::now();
+    let output = sql_lexer::sanitize_string(query);
+    let elapsed = start.elapsed();
+    println!("Output: {}", output);
+    println!("Elapsed: {:?}", elapsed);
+  }
+}