feat: batch simulate (#6599)

Closes: AztecProtocol/aztec-packages#6549

Also removes `FunctionData` from `TxExecutionRequest` and a bunch of
other places, in favor of just the `FunctionSelector`(which is actually
what's needed). This was missed from #3417 and was driving me crazy when
trying to add a few more things to `FunctionCall`. It had also leaked
somehow into the AVM enqueued calls.

aztec/src/oracle/enqueue_public_function_call.nr

@@ -80,7 +80,7 @@ pub fn parse_public_call_stack_item_from_oracle(fields: [Field; ENQUEUE_PUBLIC_F
     // there is no more data in fields because there is only ENQUEUE_PUBLIC_FUNCTION_CALL_RETURN_SIZE fields!
     let item = PublicCallStackItem {
         contract_address: AztecAddress::from_field(reader.read()),
-        function_data: reader.read_struct(FunctionData::deserialize),
+        function_data: FunctionData { selector: FunctionSelector::from_field(reader.read()), is_private: false },
         public_inputs: PublicCircuitPublicInputs {
             call_context: reader.read_struct(CallContext::deserialize),
             args_hash: reader.read(),