E2E: Add order_numeric, and order_string checks

[niklas88]

Adds simple checks for numeric and string order. Currently I just take the whole string ignoring the " and "^^xxxx but I think it's okay because all the values in an ordered column should all have the same format. What do you think?

[floriankramer]

As far as I can tell, the comparison should work for most types (including dates).
With xsd:float and xsd:decimal though neither the string nor the numeric method yield the correct order though, as for strings 900 > 1000 ist true and when trying to use the numeric method python can't parse the xsd:float as a float.

[niklas88]

@floriankramer you're right. So if I'm understanding this right, you're proposing that we detect the "xx"^^xsd:float and xsd:decimal and just take the part within the "" for the order_numeric check?