[Cashtab] [p3 local msg verify] Support xec addresses

Summary:
T2730

Depends on D12459

Similar to the last diff, dealt with some complications, so required a few things to get this to an MVP increment.

1. Renamed bitcoinjs-message to xecjs-message
2. Removed the npm dependency standard from xecjs-message as it was testing for formatting distinct from that used in the bitcoin-abc monorepo
3. Updated xecjs-message package.json file to reflect its new home
4. Added support for parsing xec addresses to the verify function in xecjs-message
5. Removed address translating from the call to xecjs-message in SignVerifyMsg.js

Test Plan:
npm start
Sign and verify a few messages. Confirm in dev log that both outputs give same result.

Note: both methods still do not support ecash signed msgs, this will be resolved later in the stack

Reviewers: #bitcoin_abc, emack

Reviewed By: #bitcoin_abc, emack

Differential Revision: https://reviews.bitcoinabc.org/D12460