New (and much improved) layout for Add funds... dialog

[bradleyrichter]

This dialog has many improvements based on feedback from Twitter user reports.

• some users were drawn to the coinbase logo and clicked, expecting to send a payment from their existing CB wallet
• original button text for the CB buy widget was "Buy With Coinbase" and may be misleading people to think this is the button to use their existing CB account
• the large QR code may have pushed users to the first option simply because they assumed it was not useful to them, thus entering the wrong path based on subconscious process of elimination.
• customers outside of the USA are denied access to the CB buy widget so we want to hide that option for users outside of the USA.

New items:

• hid the QR code under a new sub-dialog
• added app buttons if user does want to use the QR code with their phone
• created clear separation between using the QR code and the button to either copy the brave wallet address or send it through the URI handler
• Changed the title to immediately call out the "Three ways"
• added concise options text
• added footnote text
• reduced CB logo and moved it to the bottom of the dialog
• refined layout and button styles