Add SWO support for the k20dx HIC

It appears that there is support for this in the k26 target via software, but not for the k20. We're looking to see if/how SWO support for the k20 is possible.

@maclobdell @brianesquilona @loverdeg-ep @trowbridgec

Start by locating the k26 target's software SWO support and compare its implementation and assumptions with the k20 target. Investigate whether the k20 HIC can provide equivalent SWO support; done means establishing a clear feasibility result and, if feasible, defining the required implementation work.

Written by the indexing model from the issue text.