bug: estimate_fee should keep state changes between two tx when doing bulk estimate

[tdelabro]

Bug Report

Madara version: 0.4.0

Current behavior:

The RPC route estimate_fee receives a vec of tx to estimate.
We spawn one instance of the runtime for each tx.
This means that the state is reset between each estimated transaction.

Expected behavior:

The state should not reset. Tx number n should be executed on a state changed by tx number n-1

Steps to reproduce:

Call estimate fee with multiple tx from the same account, while increasing the nonce for each tx.
It will fail because the second will have nonce = 1 when the runtime expect nonce = 0.

Related code:

the loop in crates/client/rpc/src/lib.rs, fn estimate_fee: for tx in request {...} should happen inside crates/pallets/starknet/src/lib.rs, fn estimate_fee.

it's signature should be changed to:

    pub fn estimate_fee(transaction: Vec<UserTransaction>) -> Result<Vec<(u64, u64)>, DispatchError>;

Other information: