CI: build a test artifact (#527)

* CI: build a test artifact

* CI: try building before testing

* CI: try proper bin name

* CI: preempty cache to benchmark properly

* CI: run build after test

* CI: change target source

* CI: try build before test once again

* CI: chore

* CI: prepopulate target cache

* CI: conditional build; aws sync

* CI: mock building to test publishing

* CI: lacks permissions in the other job

* CI: undebug