RFR: 5641: Rule that looks at G1 MMU Information

Fri May 26 20:44:07 UTC 2023

This PR addresses JMC-5641 [[0]](https://bugs.openjdk.org/browse/JMC-5641), in which it would be nice to have a rule that looks at g1mmu information. Specifically, the issue makes note that this rule should compare gcTime of pauses and check if the pause time is over the target.

Example result when okay:
![g1mmu_okay](https://github.com/openjdk/jmc/assets/10425301/7b371027-d992-4d70-84fe-f8ad9ffb4088)

Example result when warning:
![g1mmu_warning](https://github.com/openjdk/jmc/assets/10425301/15803bc4-2d4f-4e53-9944-c97347564e39)

[0] https://bugs.openjdk.org/browse/JMC-5641

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Commit messages:
 - 5641: Rule that looks at G1 MMU Information

Changes: https://git.openjdk.org/jmc/pull/488/files
 Webrev: https://webrevs.openjdk.org/?repo=jmc&pr=488&range=00
  Issue: https://bugs.openjdk.org/browse/JMC-5641
  Stats: 259 lines in 10 files changed: 252 ins; 1 del; 6 mod
  Patch: https://git.openjdk.org/jmc/pull/488.diff
  Fetch: git fetch https://git.openjdk.org/jmc.git pull/488/head:pull/488

PR: https://git.openjdk.org/jmc/pull/488