My project uses integer type hash key.

Currently, if we specify integer key to hash key, we need to do below process on dynamoid

1. define hash key with table method
2. override hash key type by field method

class Model
  include Dynamoid::Document
  
  table key: :hash_key # hash_key define as string type

  field :hash_key, :integer # override hash_key type to integer from string
end

But, when we override attribute, dynamoid notice us warning message like

'Method hash_key= generated for the field hash_key overrides already existing method'
'Method hash_key generated for the field hash_key overrides already existing method'

So, I'd like to add key_type option to specify type to hash key on table method to avoid warning message.