Port/reimplement `rest.Configuration`

[lucekdudek]

• change name so it reflects what it does: Configuration -> ApiFactory
• change factory methods names so they reflect what they are doing: market() -> create_market_api()
• Copy yapapi/config.py:ApiConfig and add logic resposible for creating default ya_ urls.
• Create factories that will return specific ya_ clients based on given ApiConfig
  • Replace self._api_config.market() calls with calls to new factory. e.g.:

    self._ya_market_api = ApiFactory(self._api_config).create_market_api()