add support for bucket level request count per API (#17468)

New metrics added to calculate API request count
per bucket, per API.  Captures errors, including
4xx, 5xx HTTP status codes separately.

cmd/api-errors.go

@@ -184,6 +184,7 @@ const (
 	ErrBucketAlreadyExists
 	ErrMetadataTooLarge
 	ErrUnsupportedMetadata
+	ErrUnsupportedHostHeader
 	ErrMaximumExpires
 	ErrSlowDownRead
 	ErrSlowDownWrite
@@ -1442,6 +1443,11 @@ var errorCodes = errorCodeMap{
 		Description:    "Your metadata headers are not supported.",
 		HTTPStatusCode: http.StatusBadRequest,
 	},
+	ErrUnsupportedHostHeader: {
+		Code:           "InvalidArgument",
+		Description:    "Your Host header is malformed.",
+		HTTPStatusCode: http.StatusBadRequest,
+	},
 	ErrObjectTampered: {
 		Code:           "XMinioObjectTampered",
 		Description:    errObjectTampered.Error(),