[Cashtab] Support send token txs with bip21 query strings

Summary: Support token send txs with bip21 query strings in Cashtab

Test Plan:
npm test

This is deployed at the test site. You can also confirm that bip21 link fwding works, e.g.

https://cashtab-local-dev.netlify.app/#/send?bip21=ecash:qphlhe78677sz227k83hrh542qeehh8el5lcjwk72y?token_id=21c5d17f37e96279da21fd24ff4d15be2dd146b7fa59ef77f7d84546477199d2&token_decimalized_qty=1

this is also tested with npm test now tho

Reviewers: #bitcoin_abc, emack

Reviewed By: #bitcoin_abc, emack

Subscribers: emack

Differential Revision: https://reviews.bitcoinabc.org/D17219