Admin client cannot create topics with additional config

[franvila]

For Kroxylicious system tests (related to this issue: kroxylicious/kroxylicious#732) we will need to make the topics more configurable. Currently we only have --topic-partitions and --topic-rep-factor as parameters and we would like to be able to configure things like:

• min.insync.replicas
• compression type
• or any other possible configuration

For that, as a suggestion, we can use a parameter such as --config and add additional config separated by spaces:

--config=min.insync.replicas=2 compression.type=lz4 blah=2