[Cashtab] Move the token urls config out of Ticker.js

Summary: Similar to D14102, this diff moves the token specific urls out of Ticker.js and into its own config.

Test Plan:

• grep -r currency.tokenIconSubmitApi src/ and ensure no results
• grep -r currency.tokenIconsUrl src/ and ensure no results
• grep -r currency.tokenDbUrl src/ and ensure no results
• grep -r currency.newTokenDefaultUrl src/ and ensure no results
• npm test
• npm start
• create new token with icon supplied and Document URL left blank, verify new token successfully created, icon displays correctly in app and the default cashtab url is shown in explorer
• calculate new airdrop and ensure successful onchain parsing
• send a token

Reviewers: bytesofman, #bitcoin_abc, Fabien

Reviewed By: #bitcoin_abc, Fabien

Subscribers: Fabien

Differential Revision: https://reviews.bitcoinabc.org/D14109