Give a warning when sending to a non-checksum'ed address or an address who's checksum doesn't validate the address

[bbondy]

In Ethereum an address casing is used as a checksum for validation. We should check this and if it fails give an error.

• If an input address matches the API result for KeyringController's GetChecksumEthAddress then don't give a warning
• If an address has each alphabetic character as lowercase, give a warning that the address has no checksum information and might be invalid.
• If an address has each alphabetic character as uppercase, give a warning that the address has no checksum information and might be invalid.
• If an address has both lowercase and uppercase alphabetic characters, and it doesn't match the checksum address, give an error and don't allow the user to send.

[srirambv]

Brave	1.35.89 Chromium: 97.0.4692.71 (Official Build) beta (64-bit)
Revision	adefa7837d02a07a604c1e6eff0b3a09422ab88d-refs/branch-heads/4692@{#1247}
OS	☑️ Linux	☑️ Windows 11 Version Dev (Build 22523.1000)	☑️ macOS Version 12.0.1 (Build 21C52)
Verified steps from brave/brave-core#11607 Verified entering an invalid address throws message about not a valid ETH address Verified an error is shown when the address is missing checksum or has an invalid checksum
	19532-Linux.mp4	19532-Windows.mov	19532-macOS.mov

[Ymetro]

So, then we have to ask, for instance, Binance for using casing in their deposit addresses, cause now it can only be sent by Brave Browser for PC/Mac/Linux and not by the Brave Mobile browser version 1.47 (23.2.1.14) on iOS 16.3, because after the check there is no way to proceed when asked; the sent button remains greyed out.