randgen: import plpgsql/parser to inject sql/parser.ParseDoBlockFn

We recently extended sqlsmith to generate DO blocks. Those are handled
in the sql parser via an injected function, so we need to ensure that
the injection happens. We got a test failure where usage of `randgen`
package resulted in a crash, so make it depend on the `plpgsql/parser`
to do the injection.

Release note: None

Author: yuzefovich

pkg/sql/randgen/BUILD.bazel

@@ -30,6 +30,7 @@ go_library(
         "//pkg/sql/oidext",
         "//pkg/sql/parser",
         "//pkg/sql/pgrepl/lsn",
+        "//pkg/sql/plpgsql/parser",
         "//pkg/sql/rowenc",
         "//pkg/sql/rowenc/valueside",
         "//pkg/sql/sem/cast",

pkg/sql/randgen/mutator.go

@@ -19,6 +19,9 @@ import (
 	"github.com/cockroachdb/cockroach/pkg/sql/catalog/colinfo"
 	"github.com/cockroachdb/cockroach/pkg/sql/catalog/descpb"
 	"github.com/cockroachdb/cockroach/pkg/sql/parser"
+	// Ensure that sql/parser.ParseDoBlockFn is injected from the PLpgSQL
+	// parser.
+	_ "github.com/cockroachdb/cockroach/pkg/sql/plpgsql/parser"
 	"github.com/cockroachdb/cockroach/pkg/sql/rowenc"
 	"github.com/cockroachdb/cockroach/pkg/sql/sem/idxtype"
 	"github.com/cockroachdb/cockroach/pkg/sql/sem/tree"