[crac] RFR: Extract crac functionality into OS-agnostic files [v4]

[Roman Marchenko]

> CRaC-related functionality is moved to `crac*.hpp/cpp` files, and now it is in `crac` class instead of `os`.

Roman Marchenko has refreshed the contents of this pull request, and previous commits have been removed. The incremental views will show differences compared to the previous content of the PR. The pull request contains one new commit since the last revision:

  Merge branch 'crac' into crac-extract

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Changes:
  - all: https://git.openjdk.org/crac/pull/84/files
  - new: https://git.openjdk.org/crac/pull/84/files/40db7d60..780d889b

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=crac&pr=84&range=03
 - incr: https://webrevs.openjdk.org/?repo=crac&pr=84&range=02-03

  Stats: 7 lines in 1 file changed: 0 ins; 0 del; 7 mod
  Patch: https://git.openjdk.org/crac/pull/84.diff
  Fetch: git fetch https://git.openjdk.org/crac.git pull/84/head:pull/84

PR: https://git.openjdk.org/crac/pull/84