RFR: 7116: Updating to 8.1.0

[Marcus Hirt]

Funnily enough, the revision pattern doesn't work on core, since the pom in the .m2 repo for the core components will contain the unexpanded revision variable. Didn't have time to figure out why or a workaround. This PR at least improves matters a little bit.

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Commit messages:
 - 7116: Updating to 8.1.0

Changes: https://git.openjdk.java.net/jmc/pull/206/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jmc&pr=206&range=00
  Issue: https://bugs.openjdk.java.net/browse/JMC-7116
  Stats: 435 lines in 290 files changed: 34 ins; 30 del; 371 mod
  Patch: https://git.openjdk.java.net/jmc/pull/206.diff
  Fetch: git fetch https://git.openjdk.java.net/jmc pull/206/head:pull/206

PR: https://git.openjdk.java.net/jmc/pull/206