[crac] RFR: Print peristent JAR assumptions

[Anton Kozlov]

When an application creates URLClassLoader with the JAR, the JAR file will be assumed persistent, that is, it should be available on the restore. To make this more evident, the PR adds reporting for such JARs.

I'm not a big fan of persistent files and the implications, I think it may be done better, but while they are there, better to make them more usable.

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Commit messages:
 - Update message
 - Print persistent jars on checkpoint

Changes: https://git.openjdk.org/crac/pull/38/files
 Webrev: https://webrevs.openjdk.org/?repo=crac&pr=38&range=00
  Stats: 2 lines in 1 file changed: 2 ins; 0 del; 0 mod
  Patch: https://git.openjdk.org/crac/pull/38.diff
  Fetch: git fetch https://git.openjdk.org/crac pull/38/head:pull/38

PR: https://git.openjdk.org/crac/pull/38