xmpp-parsers: Stop reexporting extra symbols

Let’s continue reexporting jid and minidom, but not their inner pub
items, users of this crate can go one level deeper if they need that.

Only xso::error::Error is still useful to reexport, as this is part of
the public API of all of our parsers.

parsers/src/bind2.rs

@@ -6,7 +6,7 @@
 
 use crate::mam;
 use crate::ns;
-use crate::Element;
+use minidom::Element;
 use xso::error::{Error, FromElementError};
 
 /// Represents the `<bind/>` element, as sent by the server in SASL 2 to advertise which features
@@ -180,7 +180,6 @@ impl From<Bound> for Element {
 #[cfg(test)]
 mod tests {
     use super::*;
-    use minidom::Element;
 
     #[cfg(target_pointer_width = "32")]
     #[test]