function addPubkeyPositionInScript(script, tss) {
  return Object.assign(
    {
      positionInScript: pubkeyPositionInScript(tss.pubkey, script),
    },
    tss,
  );
}
Adds the position of a public key in a script to a TapScriptSig object.
@param script The script in which to find the position of the public key.
@param tss The TapScriptSig object to add the position to.
@returns A TapScriptSigWitPosition object with the added position.