Remove transaction-wide byte costs

[zbuc]

As identified by @hdevalence here: https://github.com/penumbra-zone/web/pull/663#issue-2166001644 if we were to remove transaction-wide byte costs and instead have transaction costs be solely the summation of the actions included in the transaction's costs.

While looking over the work necessary to accomplish this, I noticed that we aren't even including any transaction-wide block cost at the moment:

impl GasCost for Transaction {
    fn gas_cost(&self) -> Gas {
        self.actions().map(GasCost::gas_cost).sum()
    }
}

Steps

• [ ] Determine block cost per action and set in the various GasCost impls