Improve "Entity: set new revision" plugin

Problem/Motivation

Using the Entity: set new revision in the context of the Presave content entity event works as expected.

Outside of that context, this only works when also the fields revision_uid, revision_timestamp and revision_log are set by the Entity: set field value action.

This is bad UX, because users don't know about this and also because it's much work to set this up.

Proposed resolution

If the set new revision action is being used on an entity outside of the presave entity event, this action should also set those 3 properties, if they don't have a value yet.