[crac] RFR: 8346386: [CRaC] Move CRaC’s Java code out of restricted packages [v4]

[Timofei Pushkin]

> To circumvent CRaC's limiting not-yet-standardized status:
> 1. Moved CRaC interface from `javax.crac` in `java.base` to `jdk.crac` in a new `jdk.crac` module.
> 2. Moved CRaC implementation from `jdk.crac` to `jdk.internal.crac.mirror`, both inside `java.base`. The whole CRaC implementation now resides in `jdk.internal.crac` which is exported (partially) only to the new `jdk.crac` module.

Timofei Pushkin has updated the pull request incrementally with two additional commits since the last revision:

 - Update internal CRaC Core reference
 - Update CRaC Core symbol name

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Changes:
  - all: https://git.openjdk.org/crac/pull/164/files
  - new: https://git.openjdk.org/crac/pull/164/files/7a2d7636..29e0e41b

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=crac&pr=164&range=03
 - incr: https://webrevs.openjdk.org/?repo=crac&pr=164&range=02-03

  Stats: 3 lines in 3 files changed: 0 ins; 0 del; 3 mod
  Patch: https://git.openjdk.org/crac/pull/164.diff
  Fetch: git fetch https://git.openjdk.org/crac.git pull/164/head:pull/164

PR: https://git.openjdk.org/crac/pull/164