RFR: 8080: Add support for enabling jfr on native images

Thu Jun 8 14:08:24 UTC 2023

This PR addresses JMC-8080 [[0]](https://bugs.openjdk.org/browse/JMC-8080), in which it would be nice to add support for enabling flight recorder on GraalVM native images.

Currently, trying to use the flight recording wizard on a connected native image ends up with an error dialog:
![native-image](https://github.com/openjdk/jmc/assets/10425301/a04b49db-922c-451e-89d8-0cc951e3bbda)

The proposed solution here adds checks to determine if the vm is of type Substrate VM, and check if there is a flightrecording mbean registered.

[0] https://bugs.openjdk.org/browse/JMC-8080

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Commit messages:
 - 8080: Add support for enabling jfr on native images

Changes: https://git.openjdk.org/jmc/pull/491/files
 Webrev: https://webrevs.openjdk.org/?repo=jmc&pr=491&range=00
  Issue: https://bugs.openjdk.org/browse/JMC-8080
  Stats: 72 lines in 6 files changed: 65 ins; 0 del; 7 mod
  Patch: https://git.openjdk.org/jmc/pull/491.diff
  Fetch: git fetch https://git.openjdk.org/jmc.git pull/491/head:pull/491

PR: https://git.openjdk.org/jmc/pull/491