RFR: 8305091: Change ChaCha20 cipher init behavior to match AES-GCM

[Jamil Nimeh]

This fixes an issue where the key/nonce reuse policy for SunJCE ChaCha20 and ChaCha20-Poly1305 was overly strict in enforcing no-reuse when the Cipher was in DECRYPT_MODE.  For decryption, this should be allowed and be consistent with the AES-GCM decryption initialization behavior.

- Issue: https://bugs.openjdk.org/browse/JDK-8305091
- CSR: https://bugs.openjdk.org/browse/JDK-8305822

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Commit messages:
 - 8305091: Change ChaCha20 cipher init behavior to match AES-GCM

Changes: https://git.openjdk.org/jdk/pull/13428/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=13428&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8305091
  Stats: 77 lines in 2 files changed: 31 ins; 14 del; 32 mod
  Patch: https://git.openjdk.org/jdk/pull/13428.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/13428/head:pull/13428

PR: https://git.openjdk.org/jdk/pull/13428