[Cashtab] Support for explicit slpv1 burn txs

Summary:
Add helper function to create target outputs for an slpv1 explicit burn tx. Not currently implemented.

Note: slpv1 intentional burns must consume full quantity of token input utxos in the tx.

https://github.com/badger-cash/slp-self-mint-protocol/blob/master/token-type1-burn.md

Test Plan: npm test

Reviewers: #bitcoin_abc, PiRK

Reviewed By: #bitcoin_abc, PiRK

Differential Revision: https://reviews.bitcoinabc.org/D15525