Revert "Create_pseudonym: use OTAPI_WrapCreateNym"

This reverts commit 12b78ee174199d508a34c051cfcb87c9ba675cc9.
Add gotxs/easy package for OT_ME wrappers

The `gotxs` should only wrap `OTAPI_Wrap*` methods.

This makes it easier to see which level wrapper is actually called. Also there
might be situations where need a higher-level and a lower-level wrappers and
needed, this way both can coexist.