app-layer: add methods to get status from AppLayerResult

rust/src/applayer.rs

@@ -62,6 +62,16 @@ impl AppLayerResult {
             needed: needed,
         };
     }
+
+    pub fn is_ok(self) -> bool {
+        self.status == 0
+    }
+    pub fn is_incomplete(self) -> bool {
+        self.status == 1
+    }
+    pub fn is_err(self) -> bool {
+        self.status == -1
+    }
 }
 
 impl From<bool> for AppLayerResult {