RFR: 8271419: Refactor test code for modifying CDS archive contents

[Yumin Qi]

The code for modifying CDS archive content could be used by other tests so the common code is refactored into a util class CDSArchiveUtils.

Tests: tier1,tier4

Thanks
Yumin

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Commit messages:
 - 8271419: Refactor test code for modifying CDS archive contents

Changes: https://git.openjdk.java.net/jdk/pull/4945/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=4945&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8271419
  Stats: 452 lines in 2 files changed: 229 ins; 174 del; 49 mod
  Patch: https://git.openjdk.java.net/jdk/pull/4945.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/4945/head:pull/4945

PR: https://git.openjdk.java.net/jdk/pull/4945