Feature: Add --prefix option to prefix topics and schema subjects

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Is your feature request related to a problem? Please describe.

I realize it might be nice to include a --prefix option to add a prefix to all the created topics / schema subjects. I came across this because we share a schema registry across a bunch of different confluent kafka clusters, and I was getting rejected on registering a schema subject for a topic in a different cluster. With --prefix , different people could be running datagen from the same input schema files in different clusters without stepping on each other in schema registry

Describe the solution you'd like

add a --prefix option

Additional context