Add Benchmark for Long Reads from BytesReference Stream (#71310)

Relates #70800

This reproduces the issue reported in #70800 and demonstrates that the fix in  #71181 brings
about a 5x speedup for reading `long` from a bytes reference stream when backed by a paged bytes
reference.

benchmarks/src/main/java/org/elasticsearch/common/bytes/PagedBytesReferenceBenchmark.java

@@ -0,0 +1,66 @@
+/*
+ * Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
+ * or more contributor license agreements. Licensed under the Elastic License
+ * 2.0 and the Server Side Public License, v 1; you may not use this file except
+ * in compliance with, at your election, the Elastic License 2.0 or the Server
+ * Side Public License, v 1.
+ */
+package org.elasticsearch.common.bytes;
+
+import org.elasticsearch.common.io.stream.BytesStreamOutput;
+import org.elasticsearch.common.io.stream.StreamInput;
+import org.elasticsearch.common.unit.ByteSizeUnit;
+import org.elasticsearch.common.unit.ByteSizeValue;
+import org.openjdk.jmh.annotations.Benchmark;
+import org.openjdk.jmh.annotations.BenchmarkMode;
+import org.openjdk.jmh.annotations.Fork;
+import org.openjdk.jmh.annotations.Measurement;
+import org.openjdk.jmh.annotations.Mode;
+import org.openjdk.jmh.annotations.OutputTimeUnit;
+import org.openjdk.jmh.annotations.Param;
+import org.openjdk.jmh.annotations.Scope;
+import org.openjdk.jmh.annotations.Setup;
+import org.openjdk.jmh.annotations.State;
+import org.openjdk.jmh.annotations.Warmup;
+
+import java.io.IOException;
+import java.util.concurrent.TimeUnit;
+
+@Warmup(iterations = 5)
+@Measurement(iterations = 7)
+@BenchmarkMode(Mode.AverageTime)
+@OutputTimeUnit(TimeUnit.MILLISECONDS)
+@State(Scope.Thread)
+@Fork(value = 1)
+public class PagedBytesReferenceBenchmark {
+
+    @Param(value = { "1" })
+    private int dataMb;
+
+    private BytesReference pagedBytes;
+
+    @Setup
+    public void initResults() throws IOException {
+        final BytesStreamOutput tmp = new BytesStreamOutput();
+        final long bytes = new ByteSizeValue(dataMb, ByteSizeUnit.MB).getBytes();
+        for (int i = 0; i < bytes / 8; i++) {
+            tmp.writeLong(i);
+        }
+        pagedBytes = tmp.bytes();
+        if (pagedBytes instanceof PagedBytesReference == false) {
+            throw new AssertionError("expected paged PagedBytesReference but saw [" + pagedBytes.getClass() + "]");
+        }
+    }
+
+    @Benchmark
+    public long readLong() throws IOException {
+        long res = 0L;
+        final int reads = pagedBytes.length() / 8;
+        try (StreamInput streamInput = pagedBytes.streamInput()) {
+            for (int i = 0; i < reads; i++) {
+                res = res ^ streamInput.readLong();
+            }
+        }
+        return res;
+    }
+}