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

[Ashutosh Mehra]

This patch is the first step towards having a single set of GC APIs for allocating heap space for the archived objects.
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.

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Commit messages:
 - 8309065: Move the logic to determine archive heap location from CDS to

Changes: https://git.openjdk.org/jdk/pull/14208/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=14208&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8309065
  Stats: 127 lines in 3 files changed: 36 ins; 73 del; 18 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