Merge 2 execute query functions in one. Response waiting timeout was extracted to cluster config.

Planner may split some query into range of sub queries, where subquery
execution depends on results previous subquery. Then planner analyzes
query and if it finds similar situation he appends `motion` node to plan.
If executor finds `monion` node in execution plan, he executes
motion sub-query and saves result to virtual table, which linker will be used.

Extract `Engine` interface for working with different execution engine.

Old code was removed. Integration tests was adopted to new executor