[Cashtab] Searchable, alphabetical token list

Summary:
Tokens are difficult to browse on the Token page. They are not searchable or in any kind of alphabetical order.

Improve this experience.

• Sort user tokens alphabetically by ticker
• Make tokens searchable by ticker or name, case-insensitive

Add a new integration test for <Etokens /> component to confirm expected behavior

Test Plan:
npm test

this diff is live at https://cashtab-local-dev.netlify.app/

Reviewers: #bitcoin_abc, emack

Reviewed By: #bitcoin_abc, emack

Differential Revision: https://reviews.bitcoinabc.org/D16012