Response: remove From<Result>, favor inlining

Refs: http-rs#570 (comment)

src/middleware.rs

@@ -57,9 +57,15 @@ impl<'a, State: Send + Sync + 'static> Next<'a, State> {
         Box::pin(async move {
             if let Some((current, next)) = self.next_middleware.split_first() {
                 self.next_middleware = next;
-                current.handle(req, self).await.into()
+                match current.handle(req, self).await {
+                    Ok(request) => request,
+                    Err(err) => err.into(),
+                }
             } else {
-                self.endpoint.call(req).await.into()
+                match self.endpoint.call(req).await {
+                    Ok(request) => request,
+                    Err(err) => err.into(),
+                }
             }
         })
     }

src/response.rs

@@ -327,15 +327,6 @@ impl From<Error> for Response {
     }
 }
 
-impl From<crate::Result> for Response {
-    fn from(result: crate::Result) -> Self {
-        match result {
-            Ok(res) => res,
-            Err(err) => err.into(),
-        }
-    }
-}
-
 impl From<http::Response> for Response {
     fn from(res: http::Response) -> Self {
         Self {