Make app features compatible with Ledger devices

[vishakh]

Currently, features such as send, delegate and sign & verify are only available to Beacon users. We also want them to be available to users of Ledger devices. Therefore, we need the following enhancements:

• Add a toggle to the top right of the app to switch between Ledger and Beacon.
• If the toggle is set to Ledger, then get the device address from Ledger and display it in the address field
• For send, delegate, sign and verify, use the toggle to send the request to either Ledger or Beacon.
• Ensure all the above features work with Ledger