Parameterize the class CoinTestResults class

The goal is to (optionally) initialize the class CoinTestResults with parameters that are hardcoded in the source code.

Initialisation parameters:

• main_coin_url : str
  • default should be "http://coin.ci.qt.io"
• alternate_coin_urls : List[str]
  • default should be [ "http://testresults.qt.io/coin", "http://ci-files01-hki.intra.qt.io:8080/coin/" ]

If the download from the main_coin_url fails, it should try the ones in the list, one after another. If everything fails it should return an exception.