Update conan packages and cmake
Created by: matthew-d-jones
Part of requirements for DM-1805
Updated:
- librdkafka
- trompeloeil
- fmt
- graylog-logger
and simplified CMake.
I've avoided using CONANPKG targets and instead used the fairly new cmake_find_package
generator so that PSI can still do non-Conan builds by providing their own CMake "find modules" if they wish.