RFR: 8300235: Use VarHandle access in Image(Input | Output)StreamImpl classes [v2]

[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:

  Add benchmark

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Changes:
  - all: https://git.openjdk.org/jdk/pull/12204/files
  - new: https://git.openjdk.org/jdk/pull/12204/files/3fb71333..3b3873d5

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=12204&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=12204&range=00-01

  Stats: 95 lines in 1 file changed: 95 ins; 0 del; 0 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