[Cashtab] Stop using passLoadingStatus

Summary:
Now that we have a portable custom spinner component, use this in components that take time to calculate or communicate with a server.

passLoadingStatus is confusing and, worse, does not instantly set and unset the spinner in the parent component.

Test Plan: npm test, npm start, go to airdrop screen, enter tokenId of fb4233e8a568993976ed38a81c2671587c5ad09552dedefa78760deed6ff87aa, enter amount of 10000000, spinner behaves as expected

Reviewers: #bitcoin_abc, PiRK

Reviewed By: #bitcoin_abc, PiRK

Differential Revision: https://reviews.bitcoinabc.org/D16029