sql: Make all integer and real types belong to Tarantool's `scalar`.

     * As far as Tarantool is unable to compare `integer` and `real` classes,
     make them generic `scalars`.
     * Fix `sqlite-tcl` test in `sort/nosort` part since `WITHOUT ROWID` is now
     set by default.

sql: Initialize `default_rc` in record unpack.

     * `MsgPack` conversion to `UnpackedRecord` doesn't initialize
     `default_rc`. This ends up with flakiness in where.test.lua:14.7.2
     * The same issue affects sort.test.lua, fixed by this patch.