Chore: Make cgo optional (for sqlite) (#108756)

* make cgo optional for sqlite

* update go.mod; check error code differently

* reduce api surface even more

* move test errors into sqlite package

* add a comment

pkg/storage/unified/sql/backend.go

@@ -10,9 +10,9 @@ import (
 	"time"
 
 	"github.com/go-sql-driver/mysql"
+	"github.com/grafana/grafana/pkg/util/sqlite"
 	"github.com/jackc/pgx/v5/pgconn"
 	"github.com/lib/pq"
-	"github.com/mattn/go-sqlite3"
 	"github.com/prometheus/client_golang/prometheus"
 	"go.opentelemetry.io/otel/trace"
 	"go.opentelemetry.io/otel/trace/noop"
@@ -389,9 +389,8 @@ func (b *backend) create(ctx context.Context, event resource.WriteEvent) (int64,
 
 // IsRowAlreadyExistsError checks if the error is the result of the row inserted already existing.
 func IsRowAlreadyExistsError(err error) bool {
-	var sqlite sqlite3.Error
-	if errors.As(err, &sqlite) {
-		return sqlite.ExtendedCode == sqlite3.ErrConstraintUnique
+	if sqlite.IsUniqueConstraintViolation(err) {
+		return true
 	}
 
 	var pg *pgconn.PgError