[Cashtab] Make sure snapshot changes are included in code review

Summary:
T2890

Changse to snapshots should correspond to changes to the code in any given diff. Hence, changes to snapshot files should be reviewed.

If the snapshot changes are too large to be reviewed, this means the snapshot test itself is poorly designed and should be abandoned or re-engineered.

See jest docs from task link.

Test Plan:
npm test
Confirm the command still runs

Reviewers: #bitcoin_abc, emack

Reviewed By: #bitcoin_abc, emack

Differential Revision: https://reviews.bitcoinabc.org/D12945