RFR: 8257020: [JVMCI] enable a JVMCICompiler to specify which GCs it supports [v5]

[Doug Simon]

> A number of jtreg tests require a specific GC. These tests should be ignored when EnableJVMCI is true and the JVMCI compiler does not support the required GC.
> 
> This PR adds `JVMCICompiler.isGCSupported` and makes use of it in `WhiteBox.isGCSupported`.
> 
> Prior to this PR, a test requiring a GC not yet supported by a JVMCI compiler fail as follows:
> Error occurred during initialization of VM
> JVMCI Compiler does not support selected GC: epsilon gc

Doug Simon 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 one additional commit since the last revision:

  Keep EnableJVMCI off for GCs that don't fully support JVMCI

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

Changes:
  - all: https://git.openjdk.java.net/jdk/pull/1423/files
  - new: https://git.openjdk.java.net/jdk/pull/1423/files/6e6aef0a..0ac0959e

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=1423&range=04
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=1423&range=03-04

  Stats: 9746 lines in 264 files changed: 1058 ins; 3297 del; 5391 mod
  Patch: https://git.openjdk.java.net/jdk/pull/1423.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/1423/head:pull/1423

PR: https://git.openjdk.java.net/jdk/pull/1423