Update `Japanese` translation

Currently translated at 20.9% (113 of 540 strings)

Translation: Wiki-Bot/Discord
Translate-URL: https://weblate.frisk.space/projects/wiki-bot/discord/ja/

i18n/ja.json

@@ -13,7 +13,7 @@
     ],
     "aliases": {
         "bug": [
-            "",
+            "バグ",
             " ",
             " ",
             " ",
@@ -76,29 +76,29 @@
             " "
         ],
         "random": [
-            "",
-            " ",
+            "ランダム",
+            " 🎲",
             " ",
             " ",
             " "
         ],
         "search": [
-            "",
-            " ",
+            "検索",
+            "サーチ ",
             " ",
             " ",
             " "
         ],
         "test": [
-            "",
-            " ",
+            "テスト",
+            "検証 ",
             " ",
             " ",
             " "
         ],
         "user": [
-            "",
-            " ",
+            "ユーザー",
+            "利用者 ",
             " ",
             " ",
             " "