cmd/atlas/internal/sqlparse: move parsers out #1975

Job	Run time
unit (1.22)	18s
generate-cmp	43s
lint	32s
cli	3m 4s
integration	37s
dialect-integration / integration-mysql8	2m 58s
dialect-integration / integration-mysql57	2m 45s
dialect-integration / integration-maria107	2m 47s
dialect-integration / integration-mysql56	2m 46s
dialect-integration / integration-maria102	2m 50s
dialect-integration / integration-maria103	2m 46s
dialect-integration / integration-postgres11	3m 14s
dialect-integration / integration-postgres10	3m 8s
dialect-integration / integration-postgres-ext-postgis	3m 5s
dialect-integration / integration-postgres12	3m 9s
dialect-integration / integration-postgres13	3m 2s
dialect-integration / integration-postgres14	3m 10s
dialect-integration / integration-postgres15	3m 6s
dialect-integration / integration-sqlite	2m 27s
dialect-integration / integration-tidb5	3m 25s
dialect-integration / integration-cockroach	3m 0s
dialect-integration / integration-tidb6	3m 16s
	56m 8s

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