refac add_cert (!230)

* review poka

complete comment

* review poka

remove fixme tests

* update metadata after rebase

* I do not know why these tests did not run locally

* update membership weights

* fix benchmarks also with true runtime

* fix tests

* update runtime

* update benchmarks

* split add and renew cert

remove issuer in add_cert
and more refac
the code compiles

* clean up errors and mini refac