Fix Ordinal and Integer constraints in DesignSpace

[Paul-Saves]

• Remove scaling and normalization for categorical variables in MFK
• Ruff and black the code
• Fix several mixed integer tests that were badly setup
• Add rounding in design_space for integer, ordinal or categorical variables
• Add a new ConfigSpace object (cs_vars_cate) that is fully categorical such that Integer and Ordinal Variables can take into account the design constraints defined in the original object (cs_vars). It ain't clean but it's a good workaround for now to deal with ConfigSpace 0.6.1.
• Add tests to check that Integer or Ordinal variables constraints are well taken into account!