Have had helper functions in here for awhile but was working on the best way to implement.
For a Genesis tx, I think it's best to preserve the existing SendXec function and simply load it with targetOutputs that match SLP spec. We do not need to select any token utxo inputs for a genesis tx.
Modify getSlpGenesisTargetOutput function to return to-spec target outputs for a fixed supply genesis tx. Implement in CreateTokenForm.js.
The resulting tx differs from the legacy tested tx only in having a better calculated fee.