Update the Private Kernel Tail to output Effect Sets

[PhilWindle]

The private kernel tail should output

struct KernelCircuitPublicInputsFinal {
    aggregation_object: AggregationObject, // pull this up from FinalAccumulatedData
    end_meta: FinalAccumulatedData, // add this
    end: FinalAccumulatedData, // this will be renamed to `end_app_logic`
    constants: CombinedConstantData,
    is_private: bool,
}

end_meta will contain irrevertible side effects such as the transaction nullifier, and information related to fee preparation and fee distribution.

To do this, we will set a high watermark for side effects in the "meta" phase in PrivateCircuitPublicInputs:

struct PrivateCircuitPublicInputs {
   
    call_context: CallContext,
    
    args_hash: Field,
    return_values: [Field; RETURN_VALUES_LENGTH],

    meta_hwm: u32, // add this

    read_requests: [SideEffect; MAX_READ_REQUESTS_PER_CALL],

    // ... remaining fields unchanged

}

This work is just concerned with setting up the plumbing. Therefore, the high watermark will be set to 0, and all side effects will be part of end_app_logic.

See this doc for more info