sql: fix CREATE AS sourcing crdb_internal.create_statements panic

Fixes #106168

Fixes a bug discovered in #105895 that caused a panic when running these
statements because planner.semaCtx.NameResolver was nil:
CREATE TABLE t AS SELECT * FROM crdb_internal.create_statements;
CREATE MATERIALIZED VIEW v AS SELECT * FROM crdb_internal.create_statements;

Release note (bug fix): Fix panic executing CREATE AS with
crdb_internal.create_statements source. For example:
CREATE TABLE t AS SELECT * FROM crdb_internal.create_statements;
CREATE MATERIALIZED VIEW v AS SELECT * FROM crdb_internal.create_statements;

pkg/sql/create_as_test.go

@@ -33,11 +33,7 @@ func TestCreateAsVTable(t *testing.T) {
 
 	// These are the vtables that need to be fixed.
 	// The map should be empty if all vtables are supported.
-	brokenTables := map[string]struct{}{
-		// TODO(sql-foundations): Fix nil pointer dereference.
-		//  See https://github.com/cockroachdb/cockroach/issues/106168.
-		`"".crdb_internal.create_statements`: {},
-	}
+	brokenTables := map[string]struct{}{}
 
 	ctx := context.Background()
 	testCluster := serverutils.StartNewTestCluster(t, 1, base.TestClusterArgs{})

pkg/sql/planner.go

@@ -405,6 +405,7 @@ func newInternalPlanner(
 	p.semaCtx.SearchPath = &sd.SearchPath
 	p.semaCtx.TypeResolver = p
 	p.semaCtx.FunctionResolver = p
+	p.semaCtx.NameResolver = p
 	p.semaCtx.DateStyle = sd.GetDateStyle()
 	p.semaCtx.IntervalStyle = sd.GetIntervalStyle()