RFR: JDK-8289106: Add model of class file versions to core reflection [v2]

[Joe Darcy]

> JDK-8289106: Add model of class file versions to core reflection

Joe Darcy 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 10 additional commits since the last revision:

 - Add method to map from major class file version.
 - Merge branch 'master' into JDK-8289106
 - Update phrasing.
 - Augment and correct docs.
 - Correct major versions; RELEASE_0 and RELEASE_1 are both 45.
 - Make major method public.
 - Add AccessFlag.locations(ClassFileFormatVersion)
 - Add ClassFileFormatVersion <-> Runtime.Version conversions.
 - Merge branch 'master' into JDK-8289106
 - JDK-8289106: Add model of class file versions to core reflection

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Changes:
  - all: https://git.openjdk.org/jdk/pull/9299/files
  - new: https://git.openjdk.org/jdk/pull/9299/files/cf144d66..27a8e194

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=9299&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=9299&range=00-01

  Stats: 6369 lines in 171 files changed: 3641 ins; 1373 del; 1355 mod
  Patch: https://git.openjdk.org/jdk/pull/9299.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/9299/head:pull/9299

PR: https://git.openjdk.org/jdk/pull/9299