`xs:list` deserialization does not split on all whitespace

[yuriks]

Despite the documentation explicitly mentioning that "According to the XML Schema specification, delimiters for elements is one or more space ( , \r, \n, and \t) character(s).", ListIter only actually splits on (space): simple_type.rs.

Reproducer:

use serde::Deserialize;
use quick_xml::de::from_str;

#[derive(Deserialize)]
struct Root {
    #[serde(rename = "$text")]
    items: Vec<String>,
}

fn main() {
    const TEST_XML: &str = "<Root>one two\nthree four\tfive six</Root>";

    let root: Root = from_str(TEST_XML).unwrap();
    assert_eq!(
        root.items,
        ["one", "two", "three", "four", "five", "six"]
    );
    // assertion `left == right` failed
    //  left: ["one", "two\nthree", "four\tfive", "six"]
    // right: ["one", "two", "three", "four", "five", "six"]
}

[Mingun]

Duplicate of #674