RFR: 8002277: Refactor two PBE classes to simplify maintenance [v3]

[Valerie Peng]

> This change refactors the PBES2Core and PKCS12PBECipherCore classes in SunJCE provider as requested in the bug record. Functionality should remain the same with a clearer and simplified code/control flow with less lines of code.  This should improve readability and maintenance. I enhanced one existing regression test to test more scenarios. This test would pass before the proposed change and continues to pass with the proposed changes.

Valerie Peng 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 four additional commits since the last revision:

 - Merge branch 'master' of https://github.com/openjdk/jdk into JDK-8002277
 - update copyright year for PBES2Core.java
 - Enhanced test with more decryption w/o parameters scenario.
 - 8002277: Refactor two PBE classes to simplify maintenance

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

Changes:
  - all: https://git.openjdk.java.net/jdk/pull/8521/files
  - new: https://git.openjdk.java.net/jdk/pull/8521/files/1a2b3f90..307d2765

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=8521&range=02
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=8521&range=01-02

  Stats: 126825 lines in 1830 files changed: 108724 ins; 8599 del; 9502 mod
  Patch: https://git.openjdk.java.net/jdk/pull/8521.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/8521/head:pull/8521

PR: https://git.openjdk.java.net/jdk/pull/8521