[Cashtab] Refactor unit tests for parseChronikTx

Summary:
Depends on D15253

Create array of test vectors for parseChronikTx unit tests. Mocks are updated to have tx and parsed keys, and renamed to better reflect test case

Test Plan: npm test

Reviewers: #bitcoin_abc, Fabien

Reviewed By: #bitcoin_abc, Fabien

Subscribers: Fabien

Differential Revision: https://reviews.bitcoinabc.org/D15254