Update SendPage to remove "Verifying DAP..." loading message

[ethan-tbd]

• similar to what was achieved in chore: remove polling widgets #281, we want to consolidate any consecutive loading spinners into one loading page
• currently, you can go to SendPage via the send tab in the bottom navigation bar. from here, typing in a dap (e.g. @moegrammer/didpay.me) and hitting the next button triggers a "Verifying DAP..." loading message followed by a "Fetching offerings..." loading message which means you have entered the payment flow starting at PaymentAmountPage
• the goal of this issue is to remove the "Verifying DAP..." loading message in SendPage and instead put a small loading spinner to the right of the DAP input form when resolving the DAP
  • old flow: input DAP -> hit next -> see "Verifying DAP..." -> see "Fetching offerings..." -> enter PaymentAmountPage
  • new flow: input DAP -> hit next -> see small loading spinner next to DAP input form -> see "Fetching offerings..." -> enter PaymentAmountPage