initiate transfer out implementation

[cajubelt]

As an end-user, I need to be able to initiate a transfer out from the review page.

Our existing FiatConnect partners do not require a waiting period between creating a transfer and sending the crypto for a transfer out. (Should confirm this explicitly with BitSSA and PayChant before beginning work on this.) So let's avoid over-optimizing for potential future partners that do require this, and add in the extra complexity if/when the need arises.

AC: Tapping "confirm" on the transfer review screen should

• submit a transfer out request to the provider
• send crypto to the provider
• show a spinny wheel until the tx is confirmed
• show a catch-all error screen with a retry button if the request to initiate a transfer fails, or if the tx fails for some reason
• show a success screen once the tx is confirmed, similar to this one for transfers in:

ENG:

• Verify using the mock provider in alfajores
• If the transaction fails because they don't have enough gas, send out a new quote for the total - gas fees.