RFR: 8286433: Cache certificates decoded from TLS session tickets

[Daniel Jeliński]

When a TLS server resumes a session from a stateless session ticket, it populates the `SSLSessionImpl`'s `localCerts` and `peerCerts` fields with certificates deserialized from the session ticket. These certificates are often the same across a large number of tickets.

This patch implements a certificate cache lookup for these certificates. This enables us to avoid deserializing the same certificates repeatedly, and saves memory by reusing the same certificate objects.

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Commit messages:
 - Cache received certificates

Changes: https://git.openjdk.java.net/jdk/pull/8608/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=8608&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8286433
  Stats: 26 lines in 2 files changed: 13 ins; 8 del; 5 mod
  Patch: https://git.openjdk.java.net/jdk/pull/8608.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/8608/head:pull/8608

PR: https://git.openjdk.java.net/jdk/pull/8608