refactor: convert actix-web extractors to async await

Partial Fix. Convert extractors from Futures style to async await. This implementation utilizes trait objects as return values from the refactored functions because Rust doesn't support `async fn` in traits.

Issue mozilla-services#544

src/web/extractors.rs

@@ -15,7 +15,9 @@ use actix_web::{
     Error, FromRequest, HttpMessage, HttpRequest,
 };
 
-use futures::future::{self, FutureExt, LocalBoxFuture, Ready, TryFutureExt};
+use futures::future::{self, Future, FutureExt, LocalBoxFuture, Ready, TryFutureExt};
+
+use std::pin::Pin;
 
 use lazy_static::lazy_static;
 use mime::STAR_STAR;
@@ -139,7 +141,7 @@ pub struct BsoBodies {
 impl FromRequest for BsoBodies {
     type Config = ();
     type Error = Error;
-    type Future = LocalBoxFuture<'static, Result<Self, Self::Error>>;
+    type Future = Pin<Box<dyn Future<Output = Result<BsoBodies, Self::Error>>>>;
 
     /// Extract the BSO Bodies from the request
     ///
@@ -343,7 +345,8 @@ pub struct BsoBody {
 impl FromRequest for BsoBody {
     type Config = ();
     type Error = Error;
-    type Future = LocalBoxFuture<'static, Result<BsoBody, Self::Error>>;
+    // type Future = LocalBoxFuture<'static, Result<BsoBody, Self::Error>>;
+    type Future = Pin<Box<dyn Future<Output = Result<BsoBody, Self::Error>>>>;
 
     fn from_request(req: &HttpRequest, payload: &mut Payload) -> Self::Future {
         // Only try and parse the body if its a valid content-type
@@ -868,7 +871,7 @@ pub struct BsoPutRequest {
 impl FromRequest for BsoPutRequest {
     type Config = ();
     type Error = Error;
-    type Future = LocalBoxFuture<'static, Result<BsoPutRequest, Self::Error>>;
+    type Future = Pin<Box<dyn Future<Output = Result<BsoPutRequest, Self::Error>>>>;
 
     fn from_request(req: &HttpRequest, payload: &mut Payload) -> Self::Future {
         let metrics = metrics::Metrics::from(req);
@@ -921,7 +924,7 @@ pub struct ConfigRequest {
 impl FromRequest for ConfigRequest {
     type Config = ();
     type Error = Error;
-    type Future = LocalBoxFuture<'static, Result<Self, Self::Error>>;
+    type Future = Pin<Box<dyn Future<Output = Result<ConfigRequest, Self::Error>>>>;
 
     fn from_request(req: &HttpRequest, _: &mut Payload) -> Self::Future {
         let tags = {
@@ -971,7 +974,7 @@ pub struct HeartbeatRequest {
 impl FromRequest for HeartbeatRequest {
     type Config = ();
     type Error = Error;
-    type Future = LocalBoxFuture<'static, Result<Self, Self::Error>>;
+    type Future = Pin<Box<dyn Future<Output = Result<HeartbeatRequest, Self::Error>>>>;
 
     fn from_request(req: &HttpRequest, _: &mut Payload) -> Self::Future {
         let headers = req.headers().clone();