Allow component selection from command line

When a product consists of multiple components, like the Qt SDK and some components are not installed by default, then it is necessary to write a script file. This is overly complex and error prone when using the installer in a headless, scripted environment. For instance, in a Docker container or a CI system. It is also not possible to deselect huge components like QtCreator.

Please make it simple and easy to select components and provide a properly documented command line interface for that.

While my use-case is the QtSDK installer in particular, the root cause seems to be the installer framework.