End-cap carrier board support

The end-cap powerboards use different PADIDs than the barrel (all 0). In fact, the PADID is unique per powerboard type (R0-R5). This MR adds the basic framework to account for different PADIDs to powertools. It furthermore demonstrates in the pbv3_basic_test how this is to be used. The PB type is made a test-bench variable, which then propagates it to the tests.

More MRs using the powerboard type distinction will follow. This MR relies on the changes made in !153 (merged).

This MR is based on the work of @dsperlic, many thanks!

Depends on !167 (merged), which removes a lot of warnings on my compiler.

Tagging @kkrizka