Exchangable and customizable iceoryx platform

[elfenpiff]

Brief feature description

It should be possible to support user defined iceoryx platforms. Furthermore, the iceoryx platform should unify the behavior of all platforms so that we can abstract them safely in hoofs.

To this end we need to move iceoryx platform outside of iceoryx hoofs and define them as lowest building block in iceoryx and the user shall be able to define a custom platform via cmake switch.

This issue shall provide a design document which explains how the future iceoryx platform will be structured and which task it fulfills and introduce it as a separate package. The implementation of the features in the design document will be handled in follow up issues.

Detailed information

• [ ] Create design document for the new iceoryx platform
• [ ] Create top level iceoryx platform component
• [x] See #1619 Introduce CMake switch to support user defined iceoryx platforms