RFR: [DRAFT] 8294982: Implementation of Classfile API [v6]

[Adam Sotona]

> **This pull request is not intended for immediate integration to JDK mainline.**
> 
> 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 100 commits:

 - Merge branch 'master' into JDK-8294982
 - Merge branch 'master' into JDK-8294982
 - javadoc cleanup
 - removal of AccessController::doPriviledged from ClassHierarchyResolver
 - PackageSnippets moved from jdk/classfile/snippets to jdk/classfile/snippet-files
 - removed executable
 - removed executable
 - removed executable flags and fixed whitespaces
 - removed executable flag from test/micro/org/openjdk/bench/jdk/classfile/Write.java
 - Merge branch 'classfile-api-branch' into classfile-api-initial-branch
   
   # Conflicts:
   #	README.md
   #	make/Docs.gmk
   #	test/jdk/jdk/classfile/CorpusTest.java
   #	test/jdk/jdk/classfile/LvtTest.java
   #	test/jdk/jdk/classfile/StackMapsTest.java
 - ... and 90 more: https://git.openjdk.org/jdk/compare/b17c5242...a350f5bd

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Changes: https://git.openjdk.org/jdk/pull/10982/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=10982&range=05
  Stats: 53419 lines in 323 files changed: 53418 ins; 0 del; 1 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