[mprovement] Add request QR for Read Only accounts with warning

[WietseWind]

We removed the QR with wallet address for Read Only accounts because too many users added their Exchange deposit address as read only account (despite the warning) then to show the QR and deposit from another app... Without a destination tag.

People request the return of feature. I propose we:

• Re-add the button (Request / Show QR) for Read Only accounts, just like for unactivated accounts
• If pressed on a Read Only account: ALWAYS show a warning first:

Do you own the keys to this Read Only account, or is this your exchange account?

[ I own the keys ] | [ Exchange Account ]

If people press "I own the keys" we show the QR panel.

If people press "Exchange account", we show an alert:

You cannot deposit directly to your exchange account: you need a destination tag to do so. Please get your destination tag from your exchange, and deposit manually.

[canny]

This issue has been linked to a Canny post: Re-Add QR Code Requests for Read-only accounts 🎉