[Cashtab] [p6 local msg verify] Removed unused functions from xecjs-message verify

Summary:
T2730

Depends on D12462

Remove unused functions and dependencies from xecjs-message. These functions were associated with parsing segwit signatures in verify and decoding legacy bitcoin address format.

Test Plan: Same as D12462

Reviewers: #bitcoin_abc, emack

Reviewed By: #bitcoin_abc, emack

Differential Revision: https://reviews.bitcoinabc.org/D12463