[Cashtab] Add support for Philippine Peso

Summary: Added Philippine Peso in fiatCurrencies array & object in Ticker.js. Related to task T1989.

Test Plan:
npm start
cd web/cashtab
navigate to configure page
select Philippine Peso in the Fiat Currency dropdown
ensure fiat is set to Philippine Peso & that conversion is taking place

Reviewers: bytesofman, #bitcoin_abc

Reviewed By: bytesofman, #bitcoin_abc

Differential Revision: https://reviews.bitcoinabc.org/D10548