RFR: 8294982: Implementation of Classfile API [v11]

[Adam Sotona]

> This is root pull request with Classfile API implementation, tests and benchmarks initial drop into JDK.
> 
> Following pull requests consolidating JDK class files parsing, generating, and transforming ([JDK-8294957](https://bugs.openjdk.org/browse/JDK-8294957)) will chain to this one.
> 
> Classfile API development is tracked at:
> https://github.com/openjdk/jdk-sandbox/tree/classfile-api-branch
> 
> Development branch of consolidated JDK class files parsing, generating, and transforming is at:
> https://github.com/openjdk/jdk-sandbox/tree/classfile-api-dev-branch
> 
> Classfile API [JEP](https://bugs.openjdk.org/browse/JDK-8280389) and [online API documentation](https://htmlpreview.github.io/?https://raw.githubusercontent.com/openjdk/jdk-sandbox/classfile-api-javadoc-branch/doc/classfile-api/javadoc/java.base/jdk/classfile/package-summary.html) is also available.
> 
> Please take you time to review this non-trivial JDK addition.
> 
> Thank you,
> Adam

Adam Sotona has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains 106 commits:

 - Merge branch 'master' into JDK-8294982
 - update of Java version constants
 - unification of sealed class modifiers order
 - merged JAVAC_FLAGS and EXCLUDES in Java.gmk
 - removal of Preview.java and TransPatterns.java patch
   and enabled preview for java.base
 - jdk.compiler ClassWriter patch to avoid writing PREVIEW_MINOR_VERSION to classes participating in preview
 - Merge branch 'master' into JDK-8294982
 - Merge branch 'master' into JDK-8294982
 - javadoc cleanup
 - removal of AccessController::doPriviledged from ClassHierarchyResolver
 - ... and 96 more: https://git.openjdk.org/jdk/compare/e4252bb9...80213e61

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Changes: https://git.openjdk.org/jdk/pull/10982/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=10982&range=10
  Stats: 53409 lines in 323 files changed: 53405 ins; 0 del; 4 mod
  Patch: https://git.openjdk.org/jdk/pull/10982.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/10982/head:pull/10982

PR: https://git.openjdk.org/jdk/pull/10982