Add delegation/staking statistics: total staked in committee (Nova) [medium]

[begonaalvarezd]

Description

Priority: medium

This is part 2 of 4 statistics we would like to have for delegation/staking statistics. The idea of this feature is to know how much is staked in the staking feature for the active committee

The 4 parts are:

1. total staked
2. total staked in committee
3. total delegated
4. total delegated in committee

Afaik, this needs an INX endpoint

Motivation

Improve statistics to accomodate to new IOTA 2.0 features, like delegation/staking statistics

Requirements

Open questions (optional)

Are you planning to do it yourself in a pull request?

No.