[HotStuff 2] - Add version gating for HotStuff 2

[ss-es]

What is this task and why do we need to work on it?

See #3635

What work will need to be done to complete this task?

A new version parameter for the HotStuff 2 upgrade should be added to the Versions trait, and the decide logic should be appropriately gated.

Are there any other details to include?

No response

What are the acceptance criteria to close this issue?

Decide logic is gated

Branch work will be merged to (if not the default branch)

No response