feat(lib): carry audio attributes in browse and folder listings

A browse listed each file as a name and a size, so a searcher who saw a
bitrate in a search reply lost it the moment they opened the sharer's
files. Listings (codes 5 and 37) now carry each file's attributes the
way Nicotine+ sends them, as a SharedFileEntry with name, size and
attributes in place of the (name, size) pair; the CLI's browse record
gains bitrate and duration, and the daemon protocol moves to version 2
for the new listing shape.

soulseek-rs-lib/src/message/peer/folder_contents.rs

@@ -3,6 +3,8 @@
 //! folder" in other clients asks for.
 
 use crate::message::peer::SharedDirectory;
+#[cfg(test)]
+use crate::message::peer::SharedFileEntry;
 use crate::message::peer::shared_file_list::{
     decompress_body, read_directories, write_directories,
 };
@@ -56,7 +58,18 @@ pub fn parse_folder_contents(
 fn a_folder_listing_round_trips() {
     let dirs = vec![SharedDirectory {
         name: "music\\album".to_string(),
-        files: vec![("one.flac".to_string(), 40), ("two.flac".to_string(), 50)],
+        files: vec![
+            SharedFileEntry {
+                name: "one.flac".to_string(),
+                size: 40,
+                attributes: vec![(0, 992)],
+            },
+            SharedFileEntry {
+                name: "two.flac".to_string(),
+                size: 50,
+                attributes: Vec::new(),
+            },
+        ],
     }];
     let built = build_folder_contents(7, "music\\album", &dirs);
     let mut message = Message::new_with_data(built.get_data());