RFR: 8309065: Move the logic to determine archive heap location from CDS to G1 GC [v4]

[Ashutosh Mehra]

> This patch is the first step towards having a single set of GC APIs for allocating heap space for the archived objects (See https://bugs.openjdk.org/browse/JDK-8296263).
> It moves some of the G1 specific logic from CDS to G1 gc without changing the functionality.
> 
> Changes that add/update GC APIs for handling archive heap would be introduced in upcoming patches.

Ashutosh Mehra has updated the pull request incrementally with one additional commit since the last revision:

  Add comment to alloc_archive_region()
  
  Signed-off-by: Ashutosh Mehra <asmehra at redhat.com>

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Changes:
  - all: https://git.openjdk.org/jdk/pull/14208/files
  - new: https://git.openjdk.org/jdk/pull/14208/files/82ddb97c..a414c779

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=14208&range=03
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=14208&range=02-03

  Stats: 2 lines in 1 file changed: 2 ins; 0 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/14208.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/14208/head:pull/14208

PR: https://git.openjdk.org/jdk/pull/14208