That commit broke test discovery for me.

This reverts commit ac665edb.

The FindEigen script's variable name had changed so these tests haven't
beeen built in a while.
Also disables trying to compile eingemmappeddense for complex fields.

- macro is not a function

* do not hide get_entry_ref in derived classes
* use CRTP for operator[] (this will facilitate athread safe implementation
  at some point).
* implement operator[] by get_entry_ref only in derived classes

Add missing traits + fix Stuff usage

- run it only once across builders
- set binary name via git-config.env and install it too

we need this for our clang format status report script