RFR: 8292758: put support for UNSIGNED5 format into its own header file

Fri Sep 2 00:00:16 UTC 2022

Refactor code from inside of CompressedStream into its own unit.

This code is likely to be used in future refactorings, such as JDK-8292818 (replace 96-bit representation for field metadata with variable-sized streams).

Add gtests.

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Commit messages:
 - 8292758: put support for UNSIGNED5 format into its own header file

Changes: https://git.openjdk.org/jdk/pull/10067/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=10067&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8292758
  Stats: 935 lines in 8 files changed: 797 ins; 93 del; 45 mod
  Patch: https://git.openjdk.org/jdk/pull/10067.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/10067/head:pull/10067

PR: https://git.openjdk.org/jdk/pull/10067