Proto/Block votes: represent EMAs on int64

Context

We change the representation of per-block vote EMAs from int32 to int64. This change is required for the adaptive inflation vote in order to extend the half-life of the vote because more precision than what int32 can offer is needed in this case. EMA-related parameters and storage fields of liquidity baking are also updated as collateral damage.

Manually testing the MR

The migration code can be tested using the migrate mockup command of octez-client.

Checklist

• Document the interface of any function added or modified (see the coding guidelines)
• Document any change to the user interface, including configuration parameters (see node configuration)
• Provide automatic testing (see the testing guide).
• For new features and bug fixes, add an item in the appropriate changelog (docs/protocols/alpha.rst for the protocol and the environment, CHANGES.rst at the root of the repository for everything else).
• Select suitable reviewers using the Reviewers field below.
• Select as Assignee the next person who should take action on that MR