add the random-bytes benchmark (#595)

* add the `random-bytes` benchmark

* add report

benchmarks/random-bytes.nu

@@ -0,0 +1,20 @@
+use std bench
+
+def "random bytes" [n: int]: nothing -> binary {
+    seq 1 ($n / 8 + 1)
+        | each { random integer }
+        | into binary
+        | enumerate
+        | reduce -f 0x[] {|it, acc|
+            $acc | bytes add $it.item
+        }
+        | first $n
+}
+
+let ns = [10, 100, 1_000, 10_000, 100_000]
+
+let report = $ns | each {|n|
+    bench { random bytes $n } --rounds 10 --pretty --verbose
+} | wrap time | merge ($ns | wrap n)
+
+$report