ENH Add element version to global state

[sabina-talipova]

Description

This improvement adds a new "elemental" object to the global state that stores and updates two fields isPublished and isLiveVersion. This is necessary to allow synchronous updating of nested components that support versioning.

Issues

• CMS 5.2.0-beta1. Regression test: LinkField has "Draft / Modified" label even when Elemental Block was published silverstripe-linkfield#256

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