[Cashtab] [p5 local msg verify] Support for verifying ecash signed msgs in xecjs-message verify

Summary:
T2730

Depends on D12461

Modify the verify function to return true for messages signed with ecash prefix or bitcoin prefix

Test Plan:

cd web/cashtab
npm start

In ElectrumABC, sign a message with ecash prefix
Run it through Verify
Notice in the dev log that newVerification is true, while verification is false

In cashtab, sign a message
Run it through verify
Notice that both approaches match

Reviewers: #bitcoin_abc, emack

Reviewed By: #bitcoin_abc, emack

Subscribers: emack

Differential Revision: https://reviews.bitcoinabc.org/D12462