Simple way to define proxy

[OndraM]

We may add feature to simplify setting a proxy.

Following #119, it could now be simply set as a capability inside some CustomCapabilitiesResolver class. However, one may need the proxy name (ie. based on current environment) available not only for the WebDriver instance, but for API requests etc. inside the tests (eg. in @noBrowser tests).

So we may add something like ProxyResolver setting to the config file.

[s001dxp]

+1