reduce number of middleware handlers (#13546)

- combine similar looking functionalities into single
  handlers, and remove unnecessary proxying of the
  requests at handler layer.

- remove bucket forwarding handler as part of default setup
  add it only if bucket federation is enabled.

Improvements observed for 1kiB object reads.
```
-------------------
Operation: GET
Operations: 4538555 -> 4595804
* Average: +1.26% (+0.2 MiB/s) throughput, +1.26% (+190.2) obj/s
* Fastest: +4.67% (+0.7 MiB/s) throughput, +4.67% (+739.8) obj/s
* 50% Median: +1.15% (+0.2 MiB/s) throughput, +1.15% (+173.9) obj/s
```

cmd/auth-handler.go

@@ -487,6 +487,26 @@ func setAuthHandler(h http.Handler) http.Handler {
 	// handler for validating incoming authorization headers.
 	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 		aType := getRequestAuthType(r)
+		if aType == authTypeSigned || aType == authTypeSignedV2 || aType == authTypeStreamingSigned {
+			// Verify if date headers are set, if not reject the request
+			amzDate, errCode := parseAmzDateHeader(r)
+			if errCode != ErrNone {
+				// All our internal APIs are sensitive towards Date
+				// header, for all requests where Date header is not
+				// present we will reject such clients.
+				writeErrorResponse(r.Context(), w, errorCodes.ToAPIErr(errCode), r.URL)
+				atomic.AddUint64(&globalHTTPStats.rejectedRequestsTime, 1)
+				return
+			}
+			// Verify if the request date header is shifted by less than globalMaxSkewTime parameter in the past
+			// or in the future, reject request otherwise.
+			curTime := UTCNow()
+			if curTime.Sub(amzDate) > globalMaxSkewTime || amzDate.Sub(curTime) > globalMaxSkewTime {
+				writeErrorResponse(r.Context(), w, errorCodes.ToAPIErr(ErrRequestTimeTooSkewed), r.URL)
+				atomic.AddUint64(&globalHTTPStats.rejectedRequestsTime, 1)
+				return
+			}
+		}
 		if isSupportedS3AuthType(aType) || aType == authTypeJWT || aType == authTypeSTS {
 			h.ServeHTTP(w, r)
 			return