RFR: 8254234 - Add test library stream object builder [v2]

[Chris Hegarty]

> It is useful to have a test library facility for building stream objects, suitable for deserialization testing. We
> already have a partial implementation in one of the record serialization tests, move it to the test library for more
> general use. The implementation remains partial, but can be expanded as and when needed.

Chris Hegarty has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev
excludes the unrelated changes brought in by the merge/rebase. The pull request contains three additional commits since
the last revision:

 - Merge branch 'master' into serial-byte-stream-builder
 - apply review comments
 - Initial changes for 8254234 - Add test library stream object builder

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

Changes:
  - all: https://git.openjdk.java.net/jdk/pull/561/files
  - new: https://git.openjdk.java.net/jdk/pull/561/files/557c0a4d..e47b08aa

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=561&range=01
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=561&range=00-01

  Stats: 5499 lines in 171 files changed: 3518 ins; 1019 del; 962 mod
  Patch: https://git.openjdk.java.net/jdk/pull/561.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/561/head:pull/561

PR: https://git.openjdk.java.net/jdk/pull/561