Wire vendored nuget.config through formats::nuget (#594)

crates/socket-patch-core/src/formats/nuget/mod.rs

@@ -291,6 +291,20 @@ fn decode_entities(raw: &str) -> String {
     out
 }
 
+/// Encode `value` for a double-quoted attribute: the inverse of
+/// [`parse_config`]'s decoding, so a key read as `a&b` is written back as
+/// `a&b` and keeps its identity.
+pub(crate) fn xml_attribute(value: &str) -> String {
+    value
+        .replace('&', "&")
+        .replace('"', """)
+        .replace('<', "&lt;")
+        // Literal XML attribute whitespace would be normalized to spaces.
+        .replace('\t', "&#x9;")
+        .replace('\n', "&#xA;")
+        .replace('\r', "&#xD;")
+}
+
 #[cfg(test)]
 mod tests {
     #[test]