RFR: 8090: Enhancements for agent pom

[Christoph Langer]

This is the cleanup for JMC agent in the sense of #495.

It contains:
- version bumps
- URL updates
- spotless integration

-------------

Commit messages:
 - JMC-8090

Changes: https://git.openjdk.org/jmc/pull/496/files
 Webrev: https://webrevs.openjdk.org/?repo=jmc&pr=496&range=00
  Issue: https://bugs.openjdk.org/browse/JMC-8090
  Stats: 67 lines in 1 file changed: 35 ins; 14 del; 18 mod
  Patch: https://git.openjdk.org/jmc/pull/496.diff
  Fetch: git fetch https://git.openjdk.org/jmc.git pull/496/head:pull/496

PR: https://git.openjdk.org/jmc/pull/496