At the moment we don't add tests as upcoming equality propagation
would implement enough tests for this scenario.

We don't want to mess with subqueries in projection as our query
set doesn't contain such queries. It also simplifies some
transformations (equality propagation for example).

This low-level function can be helpfull to construct rows with a
mix of references and constants.

Previously, row expressions (i.e. tuples) expected to have alias
nodes in the list. It is correct for relational node output, but
for selection filters and join conditions we don't need aliases.
So, add api to produce rows with and without aliases.

Previously, we didn't pass logaicl ID, that was incorrect we have
to generate ID first for the filter boolean expression, and then
pass it to the selection node as well.

Add a test for successfull Plan::add_union_all() run.

Also fix some documetation style

Also make a "add_bool" test fixup

We need this refactoring to move all node plan methodes to the new
Nodes structure. Otherwise we have to put a mutable lock for the
whole plan structure rather then on the nodes list. It makes
porblems with API refactoring otherwise.

Also move this Plan implementation method to expressions.

Also "set_distribution()" function is a Plan method now.

BREAKING CHANGE: move from branch-based references in the tuple to
the array-based. Also add a logical ID to all relational nodes and
keep it in all its child tuples.

Now, our reference coordination system in a tuple looks like:
- parent relational node logical ID (we don't know actual position
  in the nodes list, so use "secondary index")
- target - i.e. a position of the reffered node in the relational
  node's children list
- posirtion in the reffered relational child node output tuple

Previously distribution was calculated in the node constructor. It
is a wrong design as the tree would be transformed multiple times
and there is no reason to recalculate distribution on each step.
We need distribution only on the last transformation when we insert
Motion nodes. So, this refactoring makes tuple distribution optional
and moves distribution logic to a separate function 'set_distribution()'.

feat: migrate getting vshard count of buckets from lua to rust and added tarantool logging to proxy functions

Was fixed interaction format between lua and sbroad rust lib. In current implementation sbroad encodes query result to yaml and send it to lua app. Lua app gives yaml and decodes it to lua table. After apply this changes lua app will receive lua table and yaml transformations will not be needed.