base: fix online voting power component

[ryuash]

Not always available.

[ryuash]

Update it might be slow due to this aggregation:

subscription OnlineVotingPowerListener {
  block(offset: 0, limit: 1, order_by: {height: desc}) {
    height
    validatorVotingPowersAggregate: validator_voting_powers_aggregate {
      aggregate {
        sum {
          votingPower: voting_power
        }
      }
    }
  }
}

[ryuash]

Closing for now. Don't know if this is something i can fix

[ryuash]

Reopening to turn this in to a poll instead of a subscription