Assume Content-Type is json for endpoints that require json (#4575)

* added default content type filter

* Merge branch 'unstable' of https://github.com/sigp/lighthouse into unstable

* create custom warp json filter that ignores content type header

* cargo fmt and linting

* updated test

* updated test

* merge unstable

* merge conflicts

* workspace=true

* use Bytes instead of Buf

* resolve merge conflict

* resolve merge conflicts

* add extra error message context

* merge conflicts

* lint

common/warp_utils/src/json.rs

@@ -0,0 +1,22 @@
+use bytes::Bytes;
+use serde::de::DeserializeOwned;
+use std::error::Error as StdError;
+use warp::{Filter, Rejection};
+
+use crate::reject;
+
+struct Json;
+
+type BoxError = Box<dyn StdError + Send + Sync>;
+
+impl Json {
+    fn decode<T: DeserializeOwned>(bytes: Bytes) -> Result<T, BoxError> {
+        serde_json::from_slice(&bytes).map_err(Into::into)
+    }
+}
+
+pub fn json<T: DeserializeOwned + Send>() -> impl Filter<Extract = (T,), Error = Rejection> + Copy {
+    warp::body::bytes().and_then(|bytes: Bytes| async move {
+        Json::decode(bytes).map_err(|err| reject::custom_deserialize_error(format!("{:?}", err)))
+    })
+}