[Cashtab] Rebranding Token menu/button labels into eToken

Summary:
Rebranded 'Token' labels into 'eToken' across:

• Wallet.js - Wallet screen transaction history menu
• components/App.js - Main menu on bottom of web UI
• extension/App.js - Main menu on bottom of extension UI
• CreateTokenForm.js - Tokens menu and the subsequent token creation screen
• UI Snapshots updated across Tokens and CreateTokenForm

Test Plan:

• npm start
• Click on the Wallet section and check the eTokens tab is displayed next to Transaction History, then switch to Transaction History and back to eTokens
• Click on the 'eTokens' section on the bottom menu and ensure the initial 'Create eToken' label is displayed correctly
• Click on the 'Create eToken' button and ensure the final creation button at the bottom of the screen is 'Create eToken'
• npm run extension
• Repeat 1-4 in browser extension mode

Reviewers: bytesofman, O1 Bitcoin ABC, #bitcoin_abc

Reviewed By: bytesofman, O1 Bitcoin ABC, #bitcoin_abc

Differential Revision: https://reviews.bitcoinabc.org/D10296