Adds 2 new JSON critera query methods

[jwoertink]

Fixes #197

This PR adds 2 more query methods following #1015

• includes which performs WHERE jsonb @> '{"some":"json"}'
• in which performs WHERE jsonb <@ '{"some":"json"}'

Also while I was in there I decided to rename the previously added Where classes from JSON.. to Jsonb.... While reading the class names that seemed to make it a little more clear for me.

class User < BaseModel
  table do
    column preferences : JSON::Any
  end
end

# query where preferences includes this json in it
UserQuery.new.preferences.includes(JSON::Any.new({"theme" => JSON::Any.new("dark")}))

# query where preferences is included in this json
UserQuery.new.preferences.in(JSON::Any.new({"theme" => JSON::Any.new("dark")}))

[jwoertink]

One thing I was just thinking about... This operator can be used on Arrays too. Ref... If this just became the new Includes then it would work for both Arrays and Jsonb, but that also means that the old Includes using val = ANY(col) would not be an option without some sort of flag or rename or something...

[robacarp]

If they're equivalent operators, I see no reason not to simplify.