HypoPG command

Goal

• Check if the hypopg extension exists
• Automatically run the command CREATE EXTENSION hypopg;
• Register Joe commands(make commands pluggable)
• First step to refactor commands

TODO / How to implement

Index management operations:

• hypo CREATE INDEX ON hypo (id) - create a hypothetical index
• hypo desc - describe all hypothetical indexes
• hypo desc id - describe hypothetical index
• hypo drop id - drop a hypothetical index
• hypo reset - drop all hypothetical indexes

The command hypo CREATE.. will:

• run a query like SELECT * FROM hypopg_create_index('CREATE INDEX ON hypo (id)');
• return an id of the created index

Acceptance criteria