tester: support required map fields
tester: support required map fields

Starting with
https://github.com/erlang/otp/commit/a13d4a750dfdf9a2a96d1e7ec0054644187afa59
Erlang uses required and optional fields in type maps.

scalaris-team/scalaris,scalaris-team/scalaris,scalaris-team/scalaris,scalaris-team/scalaris,scalaris-team/scalaris,scalaris-team/scalaris,scalaris-team/scalaris,scalaris-team/scalaris