To enable building of public output notes in the network transaction builder, we need to add get_note_script() method do the data store (for more info see #1748). This method could look like so:

pub trait DataStore: MastForestStore {
    fn get_note_script(
        &self,
        script_root: Word,
    ) -> impl FutureMaybeSend<Result<NoteScript, DataStoreError>>;
}

This method will try to find a note script with the specified root in the data store, and if not found, return an error (e.g., DataStoreError::NoteScriptNotFound).

This method will be used in the TransactionHost::on_note_after_created(). Specifically, we'd probably need to refactor how it works with the OutputNoteBuilder because the sequence would need to be:

1. Read note parameters from the stack.
2. Try to look up the RECIPIENT in the advice map. If found, extract SCRIPT_ROOT from it.
3. Try to get the script associated with the SCRIPT_ROOT from the data store.
4. Build the output note and add it to the set of output notes tracked by the host.