Learner Credential Wallet

Update README
Upgrade React, React Native, Expo
Helpful text for setting up verifier instance, scanning QR codes, adding credentials, shared link expiration
Address Special Characters in certain badge types
Fix developer warnings
Prevent duplicate profiles w/ wallet restore
Enable scrolling on Manage Profile screen
Fix Navigation order on two different pages for accessibility
Set up test coverage
Remove Accept All Button When Only One Credential in Available Credentials Screen
Show issuer logos