feat: use spaces as virtual tables
We stop using VALUES to store temporary tuple on the storages and switch to the tarantool spaces instead. This is done to avoid the problems with the auto generated column names in VALUES, parser stack and parameters limitations.
Tarantool forbids to use multiple space engines in a single transaction. So for vinyl tables we have to use vinyl spaces as a tepmorary storage. For memtx tables we can use temporary memtx spaces.
One more important change is that we can't insert values of different numeric types in a number column (as we don't cast them as the local SQL does).
Related: #314 (closed) and #280 (closed)
Edited by Denis Smirnov