RFR: 8273401: Remove JarIndex support in URLClassPath [v2]

[wxiang]

> There is a bug for URLClassPath.findResources with JarIndex.
> With some discussions about the bug, the current priority is to remove the JAR index support in URLClassPath, 
> and don’t need to do anything to the jar tool in the short term, except just to move JarIndex to the jdk.jartool module. 
> 
> The PR includes:
> 1. remove the JarIndex support in URLClassPath
> 2. move JarIndex into  jdk.jartool module.

wxiang has updated the pull request incrementally with one additional commit since the last revision:

  Some minor changes
  
  Include:
  1. remove public for INDEX_NAME in JarFile
  2. recover the definition for INDEX_NAME in JarIndex
  3. mv the test case JarIndexMergeTest.java into test/jdk/java/util/jar

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

Changes:
  - all: https://git.openjdk.java.net/jdk/pull/5383/files
  - new: https://git.openjdk.java.net/jdk/pull/5383/files/7e11c607..cba9047d

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=5383&range=01
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=5383&range=00-01

  Stats: 12 lines in 4 files changed: 5 ins; 0 del; 7 mod
  Patch: https://git.openjdk.java.net/jdk/pull/5383.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/5383/head:pull/5383

PR: https://git.openjdk.java.net/jdk/pull/5383