[Cashtab] add support for BRL and INR fiat

Summary:
T1732

Latest traffic shows surge of users from Brazil and India. Adding their fiat currencies.

Test Plan: npm start, try switching to BRL and INR, try sending a tx in BRL and INR

Reviewers: #bitcoin_abc, majcosta

Reviewed By: #bitcoin_abc, majcosta

Subscribers: majcosta

Differential Revision: https://reviews.bitcoinabc.org/D9880