RFR: 8182621: JSSE should reject empty TLS plaintexts

[Matthew Donovan]

Added code similar to the suggested patches for empty Handshake messages. I also implemented tests to verify empty Handshake, Alert, and ChangeCipherSpec messages result in expected behavior: for SSLEngineImpl, exceptions are thrown, for SSLSockets the connection is closed.

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Commit messages:
 - removed whitespace
 - removed unnecessary code
 - 8182621: JSSE should reject empty TLS plaintexts

Changes: https://git.openjdk.org/jdk/pull/13306/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=13306&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8182621
  Stats: 644 lines in 4 files changed: 642 ins; 0 del; 2 mod
  Patch: https://git.openjdk.org/jdk/pull/13306.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/13306/head:pull/13306

PR: https://git.openjdk.org/jdk/pull/13306