feat: verification email

[rayrunzewang]

Added (dynamic) email verification function

• When a user press Sign up button Then the system will verify the user email
• And upon successful verification of email, the system will give a notification of “We have sent you a verification email” and a “Finished sign-up. Ready to trade” button (direct to sign-in page)
• Verify through email link
• When a new user click on the verification link (”Verify now”) Then a user's account should be created
• And the system should direct to successful sign-up page
• And a sign-in button “Back to login” which will direct to sign-in page.
• fix AccountButton UI, for 'Create Account' and 'Back to Login' and 'Finished sign-up. Ready to trade'

Resolve CP 8