feat: improve visualization of tags

Previously tags where very much focused on color coding email and less about
adding additional information. They were also visualized in different ways in
different locations.

This commit gets rid of all "Color-coding" references, aligns visualization of
the tags across the whole project and tries to improve user experience of using
tags in general.

A search box is shown in the tagging control so the user can quickly search for
a tag if they have a huge (more than 10) amount of tags.

locales/ja/common.json

@@ -325,11 +325,11 @@
     "view_contact": "連絡先を表示",
     "message_details": "メッセージの詳細",
     "more_reply_options": "その他の返信オプション",
-    "set_color": "ラベルを設定",
+    "set_tag": "ラベルを設定",
     "tag": "ラベル",
     "more_actions": "その他の操作",
     "move_to": "移動...",
-    "remove_color": "ラベルを削除",
+    "remove_tag": "ラベルを削除",
     "more_count": "他{count}件",
     "characters_count": "{count}文字",
     "quick_reply_placeholder": "クイック返信を入力...",
@@ -398,17 +398,6 @@
       "message_id": "メッセージID",
       "list_info": "リスト情報"
     },
-    "color_tag": {
-      "title": "カラータグ",
-      "red": "赤",
-      "orange": "オレンジ",
-      "yellow": "黄色",
-      "green": "緑",
-      "blue": "青",
-      "purple": "紫",
-      "pink": "ピンク",
-      "none": "なし"
-    },
     "tooltips": {
       "reply": "返信",
       "reply_all": "全員に返信 (a)",
@@ -2033,8 +2022,7 @@
     "delete": "削除",
     "mark_as_spam": "迷惑メールを報告",
     "not_spam": "迷惑メールでない",
-    "color_tag": "ラベル",
-    "remove_color": "ラベルを削除",
+    "tag": "ラベル",
     "items_selected": "{count}件のメールを選択",
     "edit_draft": "下書きを編集",
     "cancel_scheduled_send": "送信をキャンセル",