[Cashtab] Combine useWallet hook tests in one file

Summary:
T3444

Combine these tests into one file to take advantage of standardized before and after functions

To make this diff: ctrl+c and ctrl+v the tests from useWallet.test.js to the bottom of useWalletStorage.test.js, along with required imports, then renamed useWalletStorage.test.js to useWallet.test.js

Test Plan: npm test

Reviewers: #bitcoin_abc, PiRK

Reviewed By: #bitcoin_abc, PiRK

Differential Revision: https://reviews.bitcoinabc.org/D15583