Remove API Middleware (#13243)

* remove api/gateway/apimiddleware

* fix errors in api/gateway

* remove beacon-chain/rpc/apimiddleware

* fix errors in api/client/beacon

* fix errors in validator/client/beacon-api

* fix errors in beacon-chain/node

* fix errors in validator/node

* fix errors in cmd/prysmctl/validator

* fix errors in testing/endtoend

* fix all other code

* remove comment

* fix tests

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Co-authored-by: prylabs-bulldozer[bot] <58059840+prylabs-bulldozer[bot]@users.noreply.github.com>

beacon-chain/rpc/eth/beacon/handlers.go

@@ -1549,9 +1549,7 @@ func (s *Server) GetBlockRoot(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 	response := &BlockRootResponse{
-		Data: &struct {
-			Root string `json:"root"`
-		}{
+		Data: &BlockRoot{
 			Root: hexutil.Encode(root),
 		},
 		ExecutionOptimistic: isOptimistic,