Improve error handling on failed pid creation

Currently when we try to create a device & directly want to assign a pid - and the pid creation failed, we just show that the save process of the device failed. But this is not true, as the device was created & just the pid creation failed. If the user retries it is, it is even worth as it will create the very same device multiple times - still showing this kind of error.

Possible improvements:

• if the pid creation failed we want to have an error message explicitly for this
• we don't want to stay in on the new page after the "main" creation of the device was successful

This affects also:

• platforms
• configurations
• and also the basic/edit pages (but there it is less a problem, as it just updates the same device/platform/configuration multiple times - and doesn't create new ones).
• and also the copy pages for devices & platforms