Wrap the errors of knex's better-sqlite3 client as database errors

[lehni]

Errors of knex's better-sqlite3 client reached apps as the driver's SqliteError, also in 3.x, so a unique violation wasn't a UniqueViolationError. better-sqlite3 throws errors without an errno, with extended codes like SQLITE_CONSTRAINT_UNIQUE, and with messages without the SQLITE_CONSTRAINT: prefix of sqlite3. The SQLite error parsers now accept both, classifying a constraint error by its extended code or by SQLite's own message after the SQL that knex puts in front, so values in the SQL that look like an error message don't change the result. Unit tests run each constraint error in both shapes, as CI doesn't run better-sqlite3.