fix every clippy warning possible, remove io_uring as default feature

this project's codebase is so horrendous, im shocked that no one has ran
clippy at all. it had ~200 total lint warnings, some with performance
issues and unsoundness, and the rest just very ugly codebase. i have sat
down and fixed as many of these as possible and i am exhausted.
i haven't fixed some extremely complex ones, but i brought it down from
~200 to ~30.

i have also removed io_uring as a default feature due to it falling
under the same category as linux eBPF: major kernel attack surface for
minimal performance gains. this also makes it impossible to cross-compile
from macOS to Linux because io_uring does not exist in Darwin land.
there are far better ways to achieve better performance than io_uring on
the codebase level.

Signed-off-by: strawberry <june@girlboss.ceo>

src/api/client_server/keys.rs

@@ -367,7 +367,7 @@ pub(crate) async fn get_keys_helper<F: Fn(&UserId) -> bool>(
                 .bad_query_ratelimiter
                 .read()
                 .unwrap()
-                .get(&*server)
+                .get(server)
             {
                 // Exponential backoff
                 let mut min_elapsed_duration = Duration::from_secs(30) * (*tries) * (*tries);
@@ -468,7 +468,7 @@ fn add_unsigned_device_display_name(
             } else {
                 unsigned_object.insert(
                     "device_display_name".to_owned(),
-                    Some(metadata.device_id.as_str().to_string()).into(),
+                    Some(metadata.device_id.as_str().to_owned()).into(),
                 );
             }
         }