Add support for compressing to .tgz, add gio network mount example

examples/mount.rs

@@ -0,0 +1,23 @@
+use gio::prelude::*;
+use std::env;
+
+fn main() {
+    let uri = env::args().nth(1).expect("no uri provided");
+    let context = glib::MainContext::new();
+    context.block_on(async {
+        let mount_op = gio::MountOperation::new();
+        mount_op.connect_ask_password(|mount_op, message, default_user, default_domain, flags| {
+            println!(
+                "{}, {}, {}, {:?}",
+                message, default_user, default_domain, flags
+            );
+            mount_op.set_anonymous(true);
+            mount_op.reply(gio::MountOperationResult::Handled);
+        });
+        let file = gio::File::for_uri(&uri);
+        let res = file
+            .mount_enclosing_volume_future(gio::MountMountFlags::empty(), Some(&mount_op))
+            .await;
+        println!("{:?}", res);
+    });
+}