sql/sqlclient: unbox driver codec functions #1887

Job	Run time
generate-cmp	42s
cli	3m 2s
lint	36s
integration	33s
unit (1.22)	20s
dialect-integration / integration-mysql56	2m 46s
dialect-integration / integration-maria107	2m 41s
dialect-integration / integration-mysql8	3m 0s
dialect-integration / integration-maria102	2m 49s
dialect-integration / integration-maria103	2m 51s
dialect-integration / integration-mysql57	2m 55s
dialect-integration / integration-postgres-ext-postgis	3m 11s
dialect-integration / integration-postgres10	2m 57s
dialect-integration / integration-postgres11	3m 3s
dialect-integration / integration-postgres12	3m 7s
dialect-integration / integration-postgres13	3m 1s
dialect-integration / integration-postgres14	3m 11s
dialect-integration / integration-postgres15	3m 6s
dialect-integration / integration-cockroach	2m 46s
dialect-integration / integration-sqlite	2m 34s
dialect-integration / integration-tidb5	3m 18s
dialect-integration / integration-tidb6	3m 21s
	55m 50s

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