FCU should move GlobalWorldState Root

[LukaszRozmej]

Changes

• Change global world state state root on FCU

Types of changes

What types of changes does your code introduce?

• Bugfix (a non-breaking change that fixes an issue)
• New feature (a non-breaking change that adds functionality)
• Breaking change (a change that causes existing functionality not to work as expected)
• Optimization
• Refactoring
• Documentation update
• Build-related changes
• Other: Description

Testing

Requires testing

• Yes
• No

If yes, did you write tests?

• Yes
• No

Notes on testing

Please run nodes.

Documentation

Remarks

• Why didn't we implement it earlier? Probably omission.
• It doesn't matter much with current state management, it matters a lot with Paprika.

[LukaszRozmej]

Main change here

[Scooletz]

As pointed in the other PR, I'd prefer to keep one owner of the global state and leave it up to the BlockProcessor to move the root as it wants to. FCU should just notify the processor about the checkpoint being changed.