RFR: 8300235: Use VarHandle access in Image(Input | Output)StreamImpl classes [v3]

[Per Minborg]

> This PR suggests improving performance by using the newly introduced class `jdk.internal.util.ByteArray` to improve packing/unpacking operations.
> 
> The PR also proposes adding a `ByteArrayLittleEndian` class for support for little endian packing/unpacking.

Per Minborg has updated the pull request incrementally with one additional commit since the last revision:

  Fix problem in benchmark

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/12204/files
  - new: https://git.openjdk.org/jdk/pull/12204/files/3b3873d5..68d72946

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=12204&range=02
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=12204&range=01-02

  Stats: 12 lines in 1 file changed: 0 ins; 8 del; 4 mod
  Patch: https://git.openjdk.org/jdk/pull/12204.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/12204/head:pull/12204

PR: https://git.openjdk.org/jdk/pull/12204