RFR: 8121: JMC should fail properly when executed with <17 JDK

[Johannes Bechberger]

Set `osgi.requireJavaVersion` property for in `jmc.product`, so that JMC fails directly with an understandable error message when it started on a <17 JDK.

The new error message looks like the follows when running JMC on JDK 1.8:

<img width="297" alt="MicrosoftTeams-image" src="https://github.com/openjdk/jmc/assets/490655/141132a7-fcde-486b-bbe0-d78633f5a659">

I tested it with various supported and unsupported JDK versions and it worked as expected.

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Commit messages:
 - Clarify required Java version for builds
 - Set osgi required Java version

Changes: https://git.openjdk.org/jmc/pull/516/files
 Webrev: https://webrevs.openjdk.org/?repo=jmc&pr=516&range=00
  Issue: https://bugs.openjdk.org/browse/JMC-8121
  Stats: 14 lines in 2 files changed: 1 ins; 12 del; 1 mod
  Patch: https://git.openjdk.org/jmc/pull/516.diff
  Fetch: git fetch https://git.openjdk.org/jmc.git pull/516/head:pull/516

PR: https://git.openjdk.org/jmc/pull/516