Implement Cardano Stake Distribution in WASM client

[jpraynaud]

Why

The WASM client should be able to list, get details and certify Cardano stake distribution.

What

Implement the Cardano stake distribution signed entity type in the WASM Mithril client.

How

• Add the capability to handle CardanoStakeDistribution in the fake aggregator
• Implement new commands in mithril-client-wasm as unstable:
  • list_cardano_stake_distribution
  • get_cardano_stake_distribution
  • get_cardano_stake_distribution_by_epoch
  • compute_cardano_stake_distribution_message
• Add new verification step in client Manual multi-platform GitHub action