[Cashtab] Add function to generate target outputs for an slpv1 nft parent mint tx

Summary:
Add necessary function for supporting mint functionality for nft1 parent tokens. In Cashtab, this would be used by an NFT creator to increase the supply of an NFT collection.

Not yet implemented.

Test Plan: npm test

Reviewers: #bitcoin_abc, emack

Reviewed By: #bitcoin_abc, emack

Subscribers: emack

Differential Revision: https://reviews.bitcoinabc.org/D15980