Improve accessibility (#4369)

* fix(compose): Use nav and remove redundant aria-label

* fix(tabs_tab): Use nav and add aria-label

* fix(app): Add aria-label for settings toggle button

* chore: Run yarn manage:translations

app/javascript/mastodon/locales/ja.json

@@ -34,7 +34,9 @@
   "column.notifications": "通知",
   "column.public": "連合タイムライン",
   "column_back_button.label": "戻る",
+  "column_header.hide_settings": "Hide settings",
   "column_header.pin": "ピン留めする",
+  "column_header.show_settings": "Show settings",
   "column_header.unpin": "ピン留めを外す",
   "column_subheading.navigation": "ナビゲーション",
   "column_subheading.settings": "設定",
@@ -168,6 +170,7 @@
   "status.report": "通報",
   "status.sensitive_toggle": "クリックして表示",
   "status.sensitive_warning": "閲覧注意",
+  "status.share": "Share",
   "status.show_less": "隠す",
   "status.show_more": "もっと見る",
   "status.unmute_conversation": "会話のミュートを解除",