Add new Magearna shiny sprite based on Pokemon Home - move old one to gen7

data/pokemon.json

@@ -26081,6 +26081,11 @@
         "original": {
           "has_female": false,
           "has_right": false
+        },
+        "gen7": {
+          "has_female": false,
+          "has_right": false,
+          "is_unofficial_icon": true
         }
       }
     },
@@ -26091,6 +26096,10 @@
         },
         "original": {
           "is_prev_gen_icon": true
+        },
+        "gen7": {
+          "is_prev_gen_icon": true,
+          "is_unofficial_icon": true
         }
       }
     }