[Cashtab] Sort tokens alphabetically by token ticker

Summary:
Can be difficult to find a token you are looking for if your wallet has many tokens.

So, sort them alphabetically.

Test Plan:
npm test

npm start and check out the eTokens page, confirm sorting.

Reviewers: #bitcoin_abc, emack

Reviewed By: #bitcoin_abc, emack

Differential Revision: https://reviews.bitcoinabc.org/D15119