Enforce data constraints

[ManuelAlvarezC]

After this issue is solved, we should be ready to enforce data constraints on sampled data.

In order to implement them, they should be checked after data is sampled and reverse_transformed but before is returned. It should be on sdv.Sampler.sample_rows as it's the common access to the process of sampling for the three public methods. The roadmap should be as follows:

1-. Create a method sdv.Sampler.check_constraints that gets a dataframe sampled and reverse transformed and return an array of indices corresponding to rows that fulfill constraints.

2-. Modify the method sdv.Sampler.sample_rows that handles the process of sampling, but before returning the result, checks the data fullfill the constraints, discard the rows that fail and samples again until it gets to the desired number of rows.

[csala]

A functionality equivalent to this issue was added in #173 , so this can be closed now.