feat: update starknet_simulateTransactions spec for simulation flags

[greged93]

I suggest the following update to the starknet_simulateTransactions: instead of passing the flags for the starknet_simulateTransactions params as an array of SIMULATION_FLAG, change to:

{
    "type": "object",
    "properties": {
        "skip_validate": {
            "title": "Skip validation flag",
            "type": "boolean",
            "description": "Flag that indicates if the validation should be skipped for the transaction. Default value is `false`"
        },
        "skip_fee_charge": {
            "title": "Skip fee charge flag",
            "type": "boolean",
            "description": "Flag that indicates if the fee charging should be skipped for the transaction. Default value is `false`"
        },
    "required": [
        "skip_validate",
        "skip_fee_charge",
    ]
}

This would allow to pass a skip_validate and skip_fee_charge flag for each transaction that is passed to the endpoint in the array, giving more control to the user over which transactions should skip validation or fee charge.