listen to balances events to get the balance of an account

There are a lot of balances events (https://duniter.org/wiki/duniter-v2/runtime-events/)

Some of them are meaningful (transfer), some are more technical (withdraw, deposit, slash...).

Because they are common to any blockchain using the balances pallet, there is a chance that code already exist to deal with these.

Once these events are handled, we can create transaction timeseries view like what was prototyped in duniter-indexer (https://git.duniter.org/nodes/duniter-indexer/-/blob/e726bf9448f688e5df79c83e10893586eaade4e1/hasura/migrations/default/1671158661370_create_table_public_transaction_timeserie/up.sql).

If we do not take all events into account, the account balance will be false (for example not accounting for transaction fees).