Add verification when opening a payment channel

[Jaguaras]

Expected behaviour

When attempting to open a payment channel via the "CHANNELS: OUT" page and trying to enter an Alias or Node PeerID, it should give an error instructing to use only a node address that starts with "0x..".

Current behaviour

Entering an Alias, PeerID, or even random characters, after clicking "Open Channel," does not show any error. This could be misleading, causing the user to think the node isn't working properly.