[Topic create] add ability to inject extra config

[wlezzar]

This PR adds the ability to inject extra config at topic creation time. Example:

zoe topics create my-topic --partitions 5 --replication-factor 1 --config retention.ms=3600

[rsaltrelli]

How would you specify multiple configs? Like retention.ms and cleanup.policy in the same create topic command.

[rsaltrelli]

Oh, I see in the new usage. Something like this?

zoe topics create my-topic --partitions 5 --replication-factor 1 --config retention.ms=3600 --config cleanup.policy=compact

[wlezzar]

Yes exactly, it's a parameter that can be specified multiple times