[alias-server] [p12] Add mocks and unit tests including unconfirmed txs

Summary:
T2922

Depends on D13115

Additional mocks and unit tests including conflicting unconfirmed alias txs

Note: fee schedule adjusted in config.js to match current Cashtab parsing.

Test Plan:
Review unit tests and mocks
npm run test and all pass

Reviewers: #bitcoin_abc, emack

Reviewed By: #bitcoin_abc, emack

Differential Revision: https://reviews.bitcoinabc.org/D13117