Allow to define custom values for topics on datasets

[zsaltys]

Topics on datasets should be configurable in a config file and there should also be a feature flag to disable this dropdown completely.

[dlpzx]

@zsaltys Thanks for the issue. The implementation will be very similar to the one for #1013 but slightly easier as no permissions are based on topics. We will implement based on bandwidth

[zsaltys]

I would not build this and focus on the metadata form feature

[dlpzx]

Closing in favor of #1065