RFR: 8332257: Shenandoah: Move evacuation methods to implementation file [v2]

[William Kemper]

> This refactoring moves a large, complex function out of an include header. This improves build times and facilitates changes in the generational mode branch.

William Kemper 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 two additional commits since the last revision:

 - Merge remote-tracking branch 'jdk/master' into move-evacuation-to-impl
 - Do not inline evacuate_object

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Changes:
  - all: https://git.openjdk.org/jdk/pull/19240/files
  - new: https://git.openjdk.org/jdk/pull/19240/files/c28960c6..60f9111e

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=19240&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=19240&range=00-01

  Stats: 6957 lines in 146 files changed: 5240 ins; 980 del; 737 mod
  Patch: https://git.openjdk.org/jdk/pull/19240.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/19240/head:pull/19240

PR: https://git.openjdk.org/jdk/pull/19240