Hi!

First of all, thank you for your excellent work on the quick-xml project!

I'm currently working on a project where accurate error reporting would be nice. Particularly, I would like to be able to report the line and column number of any deserialization errors that occur when parsing an XML document. From what I understand, quick-xml does not support this feature directly.

However, having a similar mechanism to what serde_json and serde_toml offer, in terms of Spanned, would be great for more precise error reporting, even at the cost of some performance overheads.

Please consider this feature for future versions of quick-xml. If there is anything I can do to help (testing, design, etc.), I would be interested in contributing.

Thanks!