Provide better status updates on that first on-chain deposit

[pavlenex]

When a user deposits funds to an on-chain address, they're not aware that they need to await for certain amount of confirmations for their channel to open. It would be good to acknowledge the payment and inform users on what needs to happen for them to use he wallet.

This is the current text

Welcome to Blixt Wallet!

To get started, send on-chain funds to the bitcoin address to the right.
A channel will automatically be opened for you.

Send at least [...]

[pavlenex]

Something good to know is that this cannot be handled via notifications, so should be improved in the copy ^.

Why isn't it possible to post such notice on notification?

Notification is unfortunately a little bit tricky at the moment because of how "Neutrino" works. It doesn't listen for unconfirmed transactions.