RFR: 8311162: Simplify and modernize equals and hashCode for java.net

[Pavel Rappo]

Please review this PR to use modern APIs and language features to simplify `equals` and `hashCode` for the java.net package.

Note, in NetworkInterface we could do even more and change this:

        for (InetAddress thisAddr : this.addrs) {
            boolean found = false;
            for (InetAddress thatAddr : that.addrs) {
                if (thisAddr.equals(thatAddr)) {
                    found = true;
                    break;
                }
            }
            if (!found) {
                return false;
            }
        }
        return true;

to this:

        return Set.of(that.addrs).containsAll(Set.of(this.addrs));

But arguably, the first option is already better enough than what was there before.

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Commit messages:
 - Initial commit

Changes: https://git.openjdk.org/jdk/pull/14726/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=14726&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8311162
  Stats: 41 lines in 3 files changed: 10 ins; 18 del; 13 mod
  Patch: https://git.openjdk.org/jdk/pull/14726.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/14726/head:pull/14726

PR: https://git.openjdk.org/jdk/pull/14726