Support named salt versions
Let SaltStackVersion be the original one, not a MagicMock'ed one
Fix the warnings unit test.

Since the `warn_until` function now parses and instantiates a `SaltStackVersion`, the `bugfix` part of the version info is always shown.
Fix the `kwargs_warn_until` unit test case.
`warn_until` and `kwargs_warn_until` are now aware of named versions.

Updated the warnings tests cases accordingly.
Format `version` on deprecation messages.

Add a test case to check if a deprecation message get it's `version` format holder properly populated.
Update current deprecation messages to use named versions.
Support named version strings mathematical comparison.
Rename `version_info_or_name` to the more generic `version`.
Merge pull request #7603 from s0undt3ch/features/named-salt-versions

Add support for the future Salt named versions