RFR: 8300236: Use VarHandle access in Data(Input | Output)Stream classes [v2]

[Per Minborg]

> This PR proposes using a performance optimization using a new supported API for operations similar to those found in `java.io.Bits`

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

  Improve doc and fix typo

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Changes:
  - all: https://git.openjdk.org/jdk/pull/12076/files
  - new: https://git.openjdk.org/jdk/pull/12076/files/ce1d5765..f9280814

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=12076&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=12076&range=00-01

  Stats: 69 lines in 2 files changed: 0 ins; 37 del; 32 mod
  Patch: https://git.openjdk.org/jdk/pull/12076.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/12076/head:pull/12076

PR: https://git.openjdk.org/jdk/pull/12076