RFR: 8299576: Reimplement java.io.Bits using VarHandle access [v2]

[Per Minborg]

On Wed, 4 Jan 2023 09:01:06 GMT, Per Minborg <pminborg at openjdk.org> wrote:

>> Currently, `java.io.Bits` is using explicit logic to read/write various primitive types to/from byte arrays. Switching to the use of `VarHandle` access would provide better performance and less code. 
>> 
>> Also, using a standard API for these conversions means future `VarHandle` improvements will benefit `Bits` too. 
>> 
>> Improvements in `Bits` will propagate to `ObjectInputStream`, `ObjectOutputStream` and `RandomAccessFile`.
>> 
>> Initial benchmarks and performance discussions can be found here: https://github.com/openjdk/panama-foreign/pull/762
>
> Per Minborg has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Update copyright year in test class

Here is an update performance comparison for Linux x64:

![image](https://user-images.githubusercontent.com/7457876/210524557-cf9dbb6e-8885-484d-ae52-347b8388ef40.png)

-------------

PR: https://git.openjdk.org/jdk/pull/11840