ConfigSpace <-> ParamSet conversion

[sumny]

I do not expect this PR to get merged, therefore I open it as a draft. Provides two functions cs_to_ps and ps_to_cs that allow for ConfigSpace <-> ParamSet mappings (relying on reticulate). Maybe we can keep this PR open for some visibility, I guess some people might find it useful. Disclaimer: NOT thoroughly tested (but still better than constructing your cs/ps completely from scratch, I guess)