RFR: 8336274: MutableBigInteger.leftShift(int) optimization [v6]

[fabioromano1]

> This implementation of MutableBigInteger.leftShift(int) optimizes the current version, avoiding unnecessary copy of the MutableBigInteger's value content and performing the primitive shifting only in the original portion of the value array rather than in the value yet extended with trailing zeros.

fabioromano1 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 nine additional commits since the last revision:

 - Merge branch 'openjdk:master' into patchLeftShift
 - Merge branch 'patchLeftShift' of https://github.com/fabioromano1/jdk into patchLeftShift
 - Merge branch 'openjdk:master' into patchLeftShift
 - Restructuring tests
   
   Removed the benchmark  and rewrote the test class for MBI.leftShift() in order to use JUnit.
 - Code more clear
 - Tests changes
 - Merge branch 'openjdk:master' into patchLeftShift
 - Removed trailing whitespace
 - MutableBigInteger.leftShift(int) optimization

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/20008/files
  - new: https://git.openjdk.org/jdk/pull/20008/files/87474ee9..df35072c

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=20008&range=05
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=20008&range=04-05

  Stats: 4265 lines in 192 files changed: 2497 ins; 660 del; 1108 mod
  Patch: https://git.openjdk.org/jdk/pull/20008.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/20008/head:pull/20008

PR: https://git.openjdk.org/jdk/pull/20008