[crac] RFR: Extract crac functionality into OS-agnostic files [v2]

[Anton Kozlov]

On Fri, 16 Jun 2023 13:20:39 GMT, Roman Marchenko <rmarchenko at openjdk.org> wrote:

>> 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 incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains four additional commits since the last revision:
> 
>  - Merge branch 'crac' into crac-extract
>  - Getting rid of crac::Linux
>  - Removing trailing spaces
>  - Refactoring - extracted crac* files

Marked as reviewed by akozlov (Lead).

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PR Review: https://git.openjdk.org/crac/pull/84#pullrequestreview-1486229382