Deprecate old option `simulator` in xctool.

In version 5 of xcodebuild it was introduced new option named `-destination`. Generally this option allows to tell which iOS version and device to simulate while building project and running tests. We have already added support for this option but haven’t deprecated old options which are still treated as required.

This PR deprecates and removes the old option `simulator` which previously controlled device type against which xctool ran tests. Now it is replaced with `-destination “”name=<device name>`.