Shell: RPCs to fetch protocol activation levels

What

This MR adds two RPCs:

• GET /chain/{chain_id}/protocols to retrieve all protocol activations of the chain
• GET /chain/{chain_id}/protocols/{protocol_hash} to retrieve one protocol activation by hash

Example

> curl localhost:8732/chains/main/protocols | jq

[
  {
    "protocol": "PtParisBxoLz5gzMmn3d9WBQNoPSZakgnkMC2VNuQ3KXfUtUQeZ",
    "proto_level": 9,
    "activation_block": {
      "block_hash": "BLY1WnKYYDBRVF5fUNaob9eVXErc6BFi1Y4Wq6AAmUzFoaGKjRK",
      "level": 6422528
    }
  },
  {
    "protocol": "PsParisCZo7KAh1Z1smVd9ZMZ1HHn5gkzbM94V3PLCpknFWhUAi",
    "proto_level": 10,
    "activation_block": {
      "block_hash": "BMe5L4dgGGF7w1iLAZX6rJ31SaFLefKbDmSvMMSo1e2qAPAvUfS",
      "level": 6729729
    }
  }
]

Why

This information is useful for end users and also developers (this is something that would be useful in the rollup node and the DAL node).

How

This information is readily available in the chain store. The RPCs just expose it.