Add command for fetching compute committees

[matevz]

Currently, you can do oasis net show nodes, but you cannot determine which of those are actually elected in the (compute) committee for each ParaTime. Add something like oasis net show committee <ParaTimeID> which dumps the list of nodes in the given compute committee (and optionally for the specific block height).

[matevz]

Cheatsheet:

cc.RootHash().GetRuntimeState(ctx, &roothash.RuntimeRequest{Height: height, RuntimeID: runtimeID})

{
  "runtime": {
    ... snip descriptor ...
  },
  "genesis_block": {
    "header": {
      "version": 0,
      "namespace": "000000000000000000000000000000000000000000000000f80306c9858e7279",
      "round": 0,
      "timestamp": "2022-12-16T16:21:36+01:00",
      "header_type": 1,
      "previous_hash": "c672b8d1ef56ed28ab87c3622c5114069bdd3ad7b8f9737498d0c01ecef0967a",
      "io_root": "c672b8d1ef56ed28ab87c3622c5114069bdd3ad7b8f9737498d0c01ecef0967a",
      "state_root": "c672b8d1ef56ed28ab87c3622c5114069bdd3ad7b8f9737498d0c01ecef0967a",
      "messages_hash": "c672b8d1ef56ed28ab87c3622c5114069bdd3ad7b8f9737498d0c01ecef0967a",
      "in_msgs_hash": "c672b8d1ef56ed28ab87c3622c5114069bdd3ad7b8f9737498d0c01ecef0967a"
    }
  },
  "current_block": {
    "header": {
      "version": 0,
      "namespace": "000000000000000000000000000000000000000000000000f80306c9858e7279",
      "round": 622601,
      "timestamp": "2023-07-06T15:16:57+02:00",
      "header_type": 1,
      "previous_hash": "bdd2620678a6a495c7753bc3f2b9b501015559c1a24230b1ce499b51b2d3c9cb",
      "io_root": "e537e21170cd4e95bad8f42ed0158711cef96546abe830f0c635633a4f63bbee",
      "state_root": "6f87f15d07a4e3acc8b676cb5257262d9b6a6036a4bdd0082889ca7bc5cf8a3b",
      "messages_hash": "c672b8d1ef56ed28ab87c3622c5114069bdd3ad7b8f9737498d0c01ecef0967a",
      "in_msgs_hash": "c672b8d1ef56ed28ab87c3622c5114069bdd3ad7b8f9737498d0c01ecef0967a"
    }
  },
  "current_block_height": 14660194,
  "last_normal_round": 622601,
  "last_normal_height": 14660194,
  "executor_pool": {
    "runtime": {
      ... snip descriptor ...
    },
    "committee": {
      "kind": "executor",
      "members": [
        {
          "role": "worker",
          "public_key": "jU3L9MZTHv1v7XgbrMj/uUdUvnJmMSUmosFgjbOR3tA="
        },
        {
          "role": "worker",
          "public_key": "aUWd3B3JH+ixfplKiKKPhU+MQ866u246PT2LZd8MADI="
        },
        {
          "role": "worker",
          "public_key": "ITrwEekdZNqXrEzvw3GT6Q3AtHDd51f19nD2nVU/f0c="
        },
        {
          "role": "worker",
          "public_key": "+JOOp6OMmzldm9Dy7Cnbl/FE66bNkU0TJquOYnQIv7s="
        },
        {
          "role": "worker",
          "public_key": "4wqhqp5wDAfvQxNZUUSDmM2fVYrkxKq/tqjnnCe72Uw="
        },
        {
          "role": "backup-worker",
          "public_key": "rK6mrmCRi2dYPNraNwqg2jgEVi4sd6hi53JmT2HVGxQ="
        },
        {
          "role": "backup-worker",
          "public_key": "C+AWG4iXz590kCdbO/DAb4sBZr+umjyp683ucmawdM4="
        },
        {
          "role": "backup-worker",
          "public_key": "bKvnByvx8qwF41EqOG6wdmatGzz/qT2nbHC8i8VM65k="
        },
        {
          "role": "backup-worker",
          "public_key": "Weh9Ef8IwZaj02lgIpg9nGUpmR1YkOj3yzso8xSHdW8="
        },
        {
          "role": "backup-worker",
          "public_key": "fn3LWIvMtary53Apk1srDB/I9SxjbpYf9Tt2bH3Qkf4="
        },
        {
          "role": "backup-worker",
          "public_key": "XCiPWblWT3n1aN2NI0vslmlfV9GOkxE2Ih2SI66ZR38="
        },
        {
          "role": "backup-worker",
          "public_key": "NM/XberrrMrvavGDCYc9CX8HPT1TPz1YHWuBaDArDHc="
        }
      ],
      "runtime_id": "000000000000000000000000000000000000000000000000f80306c9858e7279",
      "valid_for": 24420
    },
    "round": 622601,
    "discrepancy": false,
    "next_timeout": 0
  },
  "liveness_stats": {
    "total_rounds": 103,
    "good_rounds": [
      103,
      88,
      103,
      103,
      103,
      103,
      103,
      103,
      103,
      103,
      103,
      103
    ]
  }
}

Extract the executors in the committee->members field.