add Dataset.from_list
_The documentation is not available anymore as the PR was closed or merged._ @albertvillanova it seems tests fail on pyarrow 6, perhaps from_pylist is a v7 method? How do you usually handle these version differences?
Added something that at least works
As discussed in #4885 

I initially added this bit at the end, thinking filling this field was necessary as it is done in from_dict. 
However, it seems the constructor takes care of filling info when it is empty.
```
if info.features is None:
  info.features = Features(
      {
          col: generate_from_arrow_type(coldata.type)
          for col, coldata in zip(pa_table.column_names, pa_table.columns)
      }
  )
```