RFR: 4936767: Parameters for MessageDigest [v6]

[Weijun Wang]

> Add parameters to `MessageDigest` and introduce `SHAKE256-LEN` with an integer parameter.

Weijun Wang has updated the pull request incrementally with two additional commits since the last revision:

 - more spec change, restruct SHAKE256.java
 - Revert "throw iape"
   
   This reverts commit d01bf93999d85081734f131873a94009d55ae364.

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Changes:
  - all: https://git.openjdk.org/jdk/pull/16660/files
  - new: https://git.openjdk.org/jdk/pull/16660/files/4f11b85d..f8c18ed0

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=16660&range=05
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=16660&range=04-05

  Stats: 86 lines in 5 files changed: 11 ins; 35 del; 40 mod
  Patch: https://git.openjdk.org/jdk/pull/16660.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/16660/head:pull/16660

PR: https://git.openjdk.org/jdk/pull/16660