Feature: Templates for Common Scenarios

[Denchick]

For testing/developmen/demot:

-- Quick setup for development:
SETUP DISTRIBUTION answers
  COLUMN TYPES VARCHAR HASH
  SHARDS shard1, shard2
  RELATION surveyme_profilesurveyanswersharded
  KEY survey_id;

-- Equivalent to:
-- CREATE DISTRIBUTION answers COLUMN TYPES VARCHAR HASH;
-- ALTER DISTRIBUTION answers ATTACH RELATION ... ;
-- CREATE KEY RANGES FOR DISTRIBUTION answers USING SHARDS shard1, shard2;

Related to: #1887

[Denchick]

We discussed this with @reshke and concluded that introducing separate commands for this is unnecessary.

Instead, we plan to provide a couple of demo applications where everything works out of the box. Users will be able to run them and easily reproduce the setup and workflow.

We believe this will make the feature much easier to understand and adopt than adding additional commands to the interface.

#2018