Add WalletConnect option to `bee-desktop`

[chrishobcroft]

Currently, it would seem that bee-desktop generates its own keypair when it loads up.

This issue is to propose that as well as this default option, there is an option for a user to connect their existing keypair using WalletConnect. This would allow a user to interact at a deeper level, by signing all transactions themselves through their smartphone, instead of it happening automatically and opaquely in the background.

Proposed user journey:

1. Open bee-desktop
2. Go to Account / Wallet
3. Select "Connect WalletConnect" (a new option)
4. Scan QR code
5. Give bee-desktop permission to connect to your wallet

Then, when performing actions which require a signature, this comes as a notification on the user's phone, allowing the user to be fully in control.

Here's how the Account / Wallet page looks right now:

Also, it might obsolete this view, as the WalletConnect link comes with it's own RPC endpoint: