Create new struct for Spec with accepted formats property

pkg/service/spec.go

@@ -0,0 +1,12 @@
+package service
+
+type Spec struct {
+	// Scope defines a scope for the image manipulation job, it can be used for logging/mertrics collection purposes
+	Scope string
+	// ImageData holds the actual image contents to processed
+	ImageData []byte
+	// Params hold the key-value pairs for the processing job and tells the manipulator what to do with the image
+	Params map[string]string
+	// AcceptedFormats have the information whether darkroom can return the image using webp or not
+	AcceptedFormats []string
+}