[alias-server] [p7] parseAliasTx and unit tests

Summary:
T2922

Depends on D13079

Implement outputScriptToAddress function in parseAliasTx and add unit tests

Test Plan: npm test

Reviewers: #bitcoin_abc, emack

Reviewed By: #bitcoin_abc, emack

Differential Revision: https://reviews.bitcoinabc.org/D13080