Add typed config

[bolshakov]

ConfigX allows you to define typed configuration using the ConfigX::Config class which uses the dry-struct library
under the hood.

class Config < ConfigX::Config
  attribute :api do 
    attribute :enabled, Types::Bool.default(false)
    attribute :endpoint, Types::String
    attribute :access_token, Types::String
  end
end 

You can then load the configuration using the load method:

config = ConfigX.load(config_class: Config)
config.api.enabled #=> true
config.api.endpoint #=> "https://example.com"

Using typed configuration allows you to define the structure of the configuration and automatically cast values to the
specified types.