RFR: 8339260: Move rarely used constants out of ClassFile [v6]

[Chen Liang]

> Many constants are cluttered in `ClassFile`. However, only a few of them are ever used by regular users, most notably `ACC_` flags and `JAVA_X_VERSION` constants. All other constants are specific and should live in more local locations, such as getters that return these constants.
> 
> This simplification of `ClassFile` constants improves user onramp to the Class-File API.
> 
> Notably, before, if `ClassFile` is static imported, `Opcode` enums must be qualified due to name clashes; this relocation allows `Opcode` enums to be static imported with `ACC_` flags, improving class file writing user experience.

Chen Liang has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains 14 commits:

 - Merge branch 'master' of https://github.com/openjdk/jdk into fix/constant-moving
 - omission in tests
 - Merge branch 'master' of https://github.com/openjdk/jdk into fix/constant-moving
 - Rename constants at new locations, link to related factories, cp tag constant names
 - Fix compile errors
 - Merge branch 'master' of https://github.com/openjdk/jdk into fix/constant-moving
 - Merge branch 'master' of https://github.com/openjdk/jdk into fix/constant-moving
 - Merge branch 'master' of https://github.com/openjdk/jdk into fix/constant-moving
 - Compile errors; now tests are all green.
 - Move Constant Pool tags to PoolEntry
   
   Two unexpected usages in jlink raw processing, but rest is fine
 - ... and 4 more: https://git.openjdk.org/jdk/compare/6fd043f1...fa9ea36d

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Changes: https://git.openjdk.org/jdk/pull/20773/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=20773&range=05
  Stats: 3473 lines in 37 files changed: 1566 ins; 901 del; 1006 mod
  Patch: https://git.openjdk.org/jdk/pull/20773.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/20773/head:pull/20773

PR: https://git.openjdk.org/jdk/pull/20773