[Cashtab] Verify Message feature

Summary: As per T2368, adding a Verify Message feature to complement the existing Sign Message function.

Test Plan:

• Navigate to Send component
• Use the Sign Message feature to sign a message using the activate wallet, noting the address, message and signature
• Enter the message, address and signature into the Verify Message feature and ensure successful verification
• enter an invalid cash address or valid etoken address and ensure error validation is triggered
• enter a signature that is not 88 characters and ensure error validation is triggered
• ensure the Verify Message button is only active when the Message is not empty, Address is a valid eCash address and the Signature is exactly 88 characters. Ensure it is inactive when one of the three fields is invalid.
• test across chrome/brave/firefox browsers and iOS/Android devices

Reviewers: bytesofman, #bitcoin_abc

Reviewed By: bytesofman, #bitcoin_abc

Differential Revision: https://reviews.bitcoinabc.org/D11287