[IMPROVEMENT] Address Verification

[gantunesr]

Description

Improve address verification in SendFlow,

1. Allow user to input an address with all lower or upper case characters.
2. If the user inputs a mixed case address, it should be the correct checksum. Else, the address should be flagged as invalid and not auto-checksum the address.

• Example of incorrect checksum: 0x87187657b35f461d0ceEc338d9B8e944A193afe2
• Example of correct checksum: 0x87187657b35F461D0Ceec338d9b8E944a193aFE2

Checklist

• There is a related GitHub issue
• Tests are included if applicable
• Any added code is fully documented

Screenshots/Recordings

Bug	Fix

Issue

Progresses https://github.com/MetaMask/mobile-planning/issues/288

[Fatxx]

Should we also add the same validation in Views/Send/index.js screen?

[gantunesr]

@Fatxx I don't see any validation logic in Views/Send/index.js and we should stop using it in favor of SendFlow

[cortisiko]

I tested these Incorrect check sum addressed:

0xa54D3c09E34aC96807c1CC397404bF2B98DC4eFb
0x87187657b35f461d0ceEc338d9B8e944A193afe2

on the send flow and also on the add contact view. I also generated QR codes for the above addresses and tested with them. See QR codes here and here. I tested upper cased addresses and lower cased addresses.

I tested scanning a keystone address QR code and I was able to successfully send to that address.

Finally I did sanity checks on:
scanning a request QR code. The correct address received the funds
Scanning an extension QR code for a couple of my accounts. I had no issues

QA passed! 🌮 🌮