Make it possible to refer to fields with space in the name on steps.row_filter formula

[aivuk]

Currently because of how row_filter is written:

            evalclass = simpleeval.EvalWithCompoundTypes
            function = lambda row: evalclass(names=row).eval(self.formula)

https://github.com/frictionlessdata/framework/blob/79c902b6bc7d6798f6e23bce1bdfd929a3998861/frictionless/steps/row/row_filter.py#L41

it's possible to refer to the fields names from a Resource in a formula passed to steps.row_filter, but if a field name has a space this make it impossible to refer to it. One simple solution would be to write:

function = lambda row: evalclass(names={c: row[c] if c != 'row' else row for c in row.flds +['row']})

and this way an user can use steps.row_filter(formula="field == '42'") or steps.row_filter(formula="row['field'] == '42'"). The first option (without row) will continue to work, but now the user has the option to refer to fields with space like in the second method.