[CPU] I64 initial support.

[nshchego]

Description

Please include a summary of the change. Please also include relevant motivation and context. See contribution guidelines for more details. If the change fixes an issue not documented in the project's Github issue tracker, please document all steps necessary to reproduce it.

Fixes # (github issue)

Checklist

General

• Do all unit and benchdnn tests (make test and make test_benchdnn_*) pass locally for each commit?
• Have you formatted the code using clang-format?

Performance improvements

• Have you submitted performance data that demonstrates performance improvements?

New features

• Have you published an RFC for the new feature?
• Was the RFC approved?
• Have you added relevant tests?

Bug fixes

• Have you included information on how to reproduce the issue (either in a github issue or in this PR)?
• Have you added relevant regression tests?

RFC PR

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