RFR: 8331608: Consolidate EncodeGCModeConcurrentFrameClosure and TransformStackChunkClosure

[Guoxiong Li]

Hi all,

After [JDK-8296875](https://bugs.openjdk.org/browse/JDK-8296875), the classes `EncodeGCModeConcurrentFrameClosure` and `TransformStackChunkClosure` almost have the same code. This patch consolidates them into one.

The tests `make test-hotspot_loom` and `make test-hotspot_gc` passed locally (linux & x64). Thanks for taking the time to review.

Best Regards,
-- Guoxiong

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Commit messages:
 - JDK-8331608

Changes: https://git.openjdk.org/jdk/pull/19084/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=19084&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8331608
  Stats: 27 lines in 1 file changed: 1 ins; 21 del; 5 mod
  Patch: https://git.openjdk.org/jdk/pull/19084.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/19084/head:pull/19084

PR: https://git.openjdk.org/jdk/pull/19084