sql: adds unique constraint checks to SCRUB

The SCRUB tool validates table constraints. Before this change, it could
only validate `CONSTRAINT` and foreign key constraints. This PR enhances
SCRUB to also validate tables that contain `PRIMARY KEY`, `UNIQUE`, or
the experimental `UNIQUE WITHOUT INDEX` keywords.

Fixes: cockroachdb#73632

Release note (sql): This PR expands the capabilities of the experimental
SCRUB tool to include checking unique constraints for primary keys,
unique indexes, and unique columns without indexes. The usage and output
of SCRUB is unchanged, but if there is a unique constraint violation,
users will see the error message `unique_constraint_violation` for all
rows that violate the constraint, along with information about the row.

Release justification:

pkg/sql/BUILD.bazel

@@ -177,6 +177,7 @@ go_library(
         "scrub_constraint.go",
         "scrub_fk.go",
         "scrub_index.go",
+        "scrub_unique_constraint.go",
         "select_name_resolution.go",
         "sequence.go",
         "sequence_select.go",
@@ -370,6 +371,7 @@ go_library(
         "//pkg/sql/schemachanger/scrun",
         "//pkg/sql/scrub",
         "//pkg/sql/sem/builtins",
+        "//pkg/sql/sem/catid",
         "//pkg/sql/sem/transform",
         "//pkg/sql/sem/tree",
         "//pkg/sql/sem/tree/treebin",
@@ -573,6 +575,8 @@ go_test(
         "//pkg/base",
         "//pkg/build/bazel",
         "//pkg/ccl/kvccl/kvtenantccl",
+        "//pkg/ccl/partitionccl",
+        "//pkg/ccl/utilccl",
         "//pkg/cloud/impl:cloudimpl",
         "//pkg/clusterversion",
         "//pkg/config",

pkg/sql/scrub.go

@@ -394,8 +394,7 @@ func createIndexCheckOperations(
 // createConstraintCheckOperations will return all of the constraints
 // that are being checked. If constraintNames is nil, then all
 // constraints are returned.
-// TODO(joey): Only SQL CHECK and FOREIGN KEY constraints are
-// implemented.
+// Only SQL CHECK, FOREIGN KEY, and UNIQUE constraints are supported.
 func createConstraintCheckOperations(
 	ctx context.Context,
 	p *planner,
@@ -443,6 +442,15 @@ func createConstraintCheckOperations(
 				constraint,
 				asOf,
 			))
+		case descpb.ConstraintTypePK:
+			fallthrough
+		case descpb.ConstraintTypeUnique:
+			results = append(results, newSQLUniqueConstraintCheckOperation(
+				tableName,
+				tableDesc,
+				constraint,
+				asOf,
+			))
 		}
 	}
 	return results, nil

pkg/sql/scrub/errors.go

@@ -42,6 +42,9 @@ const (
 	// ForeignKeyConstraintViolation occurs when a row in a
 	// table is violating a foreign key constraint.
 	ForeignKeyConstraintViolation = "foreign_key_violation"
+	// UniqueConstraintViolation occurs when a row in a table is violating
+	// a unique constraint.
+	UniqueConstraintViolation = "unique_constraint_violation"
 )
 
 // Error contains the details on the scrub error that was caught.