RFR: 8322296: Introduce CardWord for word iteration on CardTable [v3]

[Albert Mingkun Yang]

> Simple adding a new type for card-word in `CardTable` in order to avoid repeating the same logic/typedef in card based collectors.

Albert Mingkun Yang 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 five additional commits since the last revision:

 - signature
 - Merge branch 'master' into card-word
 - review
 - Merge branch 'master' into card-word
 - card-word

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Changes:
  - all: https://git.openjdk.org/jdk/pull/17144/files
  - new: https://git.openjdk.org/jdk/pull/17144/files/2b9d13e9..d709284a

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=17144&range=02
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=17144&range=01-02

  Stats: 400 lines in 37 files changed: 182 ins; 114 del; 104 mod
  Patch: https://git.openjdk.org/jdk/pull/17144.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/17144/head:pull/17144

PR: https://git.openjdk.org/jdk/pull/17144