Obsolete support for Xcode 10

[rosen-vladimirov]

Is your feature request related to a problem? Please describe.
From March/April, Apple will require using Xcode 11 to be used for building applications that will be published in AppStore.

Describe the solution you'd like
Obsolete the support for Xcode 10 and show warning message in case it is detected.

Describe alternatives you've considered
None

Additional context
None