RFR: 6778: Removing dependency on OPS4j maven repo and javax.mail:dsn

[Marcus Hirt]

Also upgrading jakarta.mail.

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Commit messages:
 - 6778: Removing dependency on OPS4j maven repo and javax.mail:dsn, also upgrading jakarta.mail

Changes: https://git.openjdk.java.net/jmc/pull/73/files
 Webrev: https://webrevs.openjdk.java.net/jmc/73/webrev.00
  Issue: https://bugs.openjdk.java.net/browse/JMC-6778
  Stats: 27 lines in 7 files changed: 1 ins; 20 del; 6 mod
  Patch: https://git.openjdk.java.net/jmc/pull/73.diff
  Fetch: git fetch https://git.openjdk.java.net/jmc pull/73/head:pull/73

PR: https://git.openjdk.java.net/jmc/pull/73