[crac] RFR: Extract crac functionality into OS-agnostic files [v5]

[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 updated the pull request with a new target base due to a merge or a rebase. The pull request now contains six commits:

 - Merge branch 'crac' into crac-extract
 - Merge branch 'crac' into crac-extract
 - Merge branch 'crac' into crac-extract
 - Getting rid of crac::Linux
 - Removing trailing spaces
 - Refactoring - extracted crac* files

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Changes: https://git.openjdk.org/crac/pull/84/files
 Webrev: https://webrevs.openjdk.org/?repo=crac&pr=84&range=04
  Stats: 2377 lines in 12 files changed: 1223 ins; 1147 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