Read mssql index columns in key order

Index.Equal compares columns by position, but the mssql GetIndexes query
had no ORDER BY, so the column order it returned was up to the query plan.

dialects/mssql.go

@@ -604,6 +604,7 @@ ON IXS.OBJECT_ID=IXCS.OBJECT_ID  AND IXS.INDEX_ID = IXCS.INDEX_ID
 INNER   JOIN sys.columns C  ON IXS.OBJECT_ID=C.OBJECT_ID
 AND IXCS.COLUMN_ID=C.COLUMN_ID
 WHERE IXS.TYPE_DESC='NONCLUSTERED' and OBJECT_NAME(IXS.OBJECT_ID) =?
+ORDER BY IXS.INDEX_ID, IXCS.IS_INCLUDED_COLUMN, IXCS.KEY_ORDINAL, IXCS.INDEX_COLUMN_ID
 `
 
 	rows, err := queryer.QueryContext(ctx, s, args...)