[cashtab-components] disable token send from badge and button

Summary: This library does not yet support token sends for eTokens (different API endpoints, different send logic in Cashtab vs badger). Until this support is added, this change is necessary to prevent the button and badge from treating attempted token sends as XEC.

Test Plan: npm run storybook, navigate to CashtabBadge --> 'price in eToken'; click "CashTab Pay" and confirm nothing happens

Reviewers: #bitcoin_abc, Fabien

Reviewed By: #bitcoin_abc, Fabien

Differential Revision: https://reviews.bitcoinabc.org/D9803