RFR: JDK-8166596: TLS support for the EdDSA signature algorithm

[Jamil Nimeh]

Hello all,
This change brings in support for certificates with EdDSA keys (both Ed25519 and Ed448) allowing those signature algorithms to be used both on the certificates themselves and used during the handshaking process for messages like CertificateVerify, ServerKeyExchange and so forth.

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Commit messages:
 - Fix cut/paste error with ECDH-RSA key exchange
 - Merge
 - Initial EdDSA/TLS solution

Changes: https://git.openjdk.java.net/jdk/pull/1197/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=1197&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8166596
  Stats: 842 lines in 9 files changed: 783 ins; 18 del; 41 mod
  Patch: https://git.openjdk.java.net/jdk/pull/1197.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/1197/head:pull/1197

PR: https://git.openjdk.java.net/jdk/pull/1197