Add option to subscribe multiple validators at once

Context:
* Currently validators can only be subscribed one by one. Meaning that someone with 50, would need to send 50 different txs, which implies: click Subscribe button, sign tx, wait, repeat. Not the best UX.

Feture:
* Add new button with `Subscribe All` that allows to subscribe all validators that are in `notsubscribed` or `untracked` state.

Tasks:
- [x] Update the abi to the latest. Latest can be found [here](https://github.com/dappnode/mev-sp-oracle/blob/main/contract/abi.abi). Its important to have this latest abi because it adds the `subscribeValidators` function.
- [x] Create new button named `Subscribe All`. No opinion where it should be placed.
- [x] When `Subscribe All` button is clicked, get all validators belonging to the connected wallet `/memory/validators/0x_wallet` (note that this is already being done) and **filter** all validators so that we get the ones in `notsubscribed` or `untracked` state. This is very important as it wouldn't make sense to subscribe an already subscribed validator. Then, get their `validator_index` eg: `validator_index(es)=5, 10, 40, 60`.
- [ ] Call the function `subscribeValidators` with said indexes and payable amount equal to `collateral_in_wei` * `length(indexes)`. As a reminder `collateral_in_wei` is already used by the contract and can be fetched from `:7300/config`

Note: `subscribeValidators` function is very similar to `subscribeValidator` with the only difference that it takes an array of validators, and that the collateral amount has to be x times the amount of validators, where x is the amount of validators one wants to subscribe.