feat!: add checkpoint_number to checkpoint with basic base layer validations

[sdbondi]

Description

• feat(validator-node): specify checkpoint number in create checkpoint request
• feat(base_layer/wallet): adds checkpoint_number to asset manager
• feat(base_layer/core): adds checkpoint number validation
• feat(base_layer/wallet): adds checkpoint number to proto files
• feat(base_layer/core): adds checkpoint_number to checkpoint

Motivation and Context

A checkpoint number provides a sequential ordering of checkpoints that is validated by the base layer.
This should make dan layer coordination of checkpointing easier and provides an indication of how much checkpoint history has existed on chain.

How Has This Been Tested?

New unit tests for the base layer validations
Manually (In progress)