DirectMemoryCRC32Digest.update(ByteBuf) allocates lots of byte[]

**FEATURE REQUEST**

1. Please describe the feature you are requesting.
Profiling shows the code block in bold is hit every time an entry is read from bookie.

```
@Override
public void update(ByteBuf buf) {
int index = buf.readerIndex();
int length = buf.readableBytes();

try {
if (buf.hasMemoryAddress()) {
// Calculate CRC directly from the direct memory pointer
crcValue = (int) updateByteBuffer.invoke(null, crcValue, buf.memoryAddress(), index, length);
} else if (buf.hasArray()) {
// Use the internal method to update from array based
crcValue = (int) updateBytes.invoke(null, crcValue, buf.array(), buf.arrayOffset() + index, length);
} else {
**// Fallback to data copy if buffer is not contiguous
byte[] b = new byte[length];
buf.getBytes(index, b, 0, length);
crcValue = (int) updateBytes.invoke(null, crcValue, b, 0, b.length);**
}
} catch (IllegalAccessException | InvocationTargetException e) {
throw new RuntimeException(e);
}
}
```
This is due to ByteBuf being marked as read only (as a result buf.hasArray() == false) from
```
ReadCompletion
public void handleV3Response(BookkeeperProtocol.Response response) {
readEntryOutstanding.dec();
ReadResponse readResponse = response.getReadResponse();
StatusCode status = response.getStatus() == StatusCode.EOK
? readResponse.getStatus() : response.getStatus();
ByteBuf buffer = Unpooled.EMPTY_BUFFER;
if (readResponse.hasBody()) {
**buffer = Unpooled.wrappedBuffer(readResponse.getBody().asReadOnlyByteBuffer());**
}
```

2. Indicate the importance of this issue to you (blocker, must-have, should-have, nice-to-have).
Are you currently using any workarounds to address this issue?

This generates lots of garbage. See attached image. Would be nice to get your thoughts on this issue, maybe using a buffer pool.

3. Provide any additional detail on your proposed use case for this feature.