RFR: 8321033: Avoid casting Array to GrowableArray [v2]

[Matias Saavedra Silva]

> `ModuleEntry::_reads` is declared as an GrowableArray<ModuleEntry*>*, but when stored in a CDS archive, it's assigned to an Array<ModuleEntry*>*. To ensure better type safety, `ModuleEntry::_reads` is changed to a generic pointer which uses two different getters and setters as well as two booleans to ensure the value is interpreted correctly. This was chosen to avoid introducing a new field to the ModuleEntry class, as another pointer and further alignment would increase the size of the ModuleEntry array. Verified with tier1-5 tests.

Matias Saavedra Silva has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains three additional commits since the last revision:

 - Merge branch 'master' into reads_8321033
 - Changed generic pointer to union
 - 8321033: Avoid casting Array to GrowableArray

-------------

Changes:
  - all: https://git.openjdk.org/jdk/pull/19549/files
  - new: https://git.openjdk.org/jdk/pull/19549/files/d564b640..73eded69

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=19549&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=19549&range=00-01

  Stats: 68280 lines in 1706 files changed: 41523 ins; 18988 del; 7769 mod
  Patch: https://git.openjdk.org/jdk/pull/19549.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/19549/head:pull/19549

PR: https://git.openjdk.org/jdk/pull/19549