Type overrides for XMLProvider #1323

In certain cases, the XmlProvider infers an incorrect type. For example:

<postalCode>10900</postalCode>

Is parsed as an integer. This creates errors when parsing postal codes starting with 0, e.g.: 01015. I have tried adding a dummy postal code into my data:

<postalCode>ABCDE</postalCode>

but this has only resulted in a bigger mess, where the value can be either an Option<string> or Option<int>. Unfortunately, we have no XSD schemas available and reverse engineering them would take too much time, as there is a large amount of different XML files.

Could you add a way to override the type of an XML element? Perhaps, similarly to how you can rename fields in the CsvProvider.