RFR: 8271073: Improve testing with VM option VerifyArchivedFields [v3]

[Ioi Lam]

> - Changed the definition of `VerifyArchivedFields` from a whacky use of `bool` to an `int` and properly define its three levels:
>   - 0: No verification 
>   - 1: Basic verification with VM_Verify (no side effects)
>   - 2: Detailed verification by forcing a GC (with side effects)
> - Changed the default value to 0. The functionality checked by this flag has been very stable so there's no need to verify it in every single test case.
> - Enabled `-XX:VerifyArchivedFields=1` for all CDS test cases.
> - Added a new test case for `-XX:VerifyArchivedFields=2` .
> - Also added comments about that this flag is suppose to check for.

Ioi Lam has updated the pull request incrementally with one additional commit since the last revision:

  added range(0,2) for VerifyArchivedFields

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

Changes:
  - all: https://git.openjdk.java.net/jdk/pull/5514/files
  - new: https://git.openjdk.java.net/jdk/pull/5514/files/d7cd3a5b..b99f8db2

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=5514&range=02
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=5514&range=01-02

  Stats: 1 line in 1 file changed: 1 ins; 0 del; 0 mod
  Patch: https://git.openjdk.java.net/jdk/pull/5514.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/5514/head:pull/5514

PR: https://git.openjdk.java.net/jdk/pull/5514