0042_snapshot.json spelled one table's check-constraint key
`checkConstraints` instead of `checkConstraint`. drizzle-kit rejects the
whole folder over it and exits 0 with only a printed message, so
`migration:mysql:generate` has silently produced nothing since #6192.
Every mysql migration authored since then was therefore hand-written with
no snapshot, including 0044 and 0045. Without those snapshots the next
generate diffs against 0043 and re-emits the assistant tables.
Adds the two missing snapshots and a test covering the invariants: journal
and .sql files agree both ways, every entry has a snapshot, indexes are
gap-free, and snapshots agree on the key spelling. The same test would have
caught the v1.70.0 release that shipped 0042_add_widget_secret.sql without
a journal entry, leaving upgraded MySQL instances with no widget_secret
table.
Thomas Camlong
a4a53af79d