feat(auto): equalizer folder in the browse tree, one toggle on playback

On-device feedback: two identical icons on the car's now-playing screen,
one of which looked dead. It worked -- but head units render custom
actions icon-first, so cycling six presets behind one static glyph was
invisible.

A monochrome icon cannot encode which of six presets is active. Android
Auto separates the idioms deliberately: custom actions for stateless
toggles, browsable lists for choosing among options.

- Playback screen keeps one action: equalizer on/off, state-aware icons
- New Ecualizador folder lists Desactivar plus the six presets by name,
  active one marked
- The preset-cycling action and its drawable are removed

Supersedes the redesign's no-equalizer-folder rule, which predated
knowing custom actions do not surface state in a car.

# Conflicts:
#	lib/l10n/app_ar.arb
#	lib/l10n/app_bn.arb
#	lib/l10n/app_de.arb
#	lib/l10n/app_en.arb
#	lib/l10n/app_es.arb
#	lib/l10n/app_fr.arb
#	lib/l10n/app_hi.arb
#	lib/l10n/app_id.arb
#	lib/l10n/app_it.arb
#	lib/l10n/app_ja.arb
#	lib/l10n/app_pt.arb
#	lib/l10n/app_ru.arb
#	lib/l10n/app_zh.arb

lib/l10n/app_ja.arb

@@ -874,5 +874,6 @@
   },
   "alarmDiagnosticsFixAction": "修正する",
   "alarmDiagnosticsIntentUnavailable": "この端末では設定画面を開けませんでした。設定アプリ内で手動で探してみてください。",
-  "alarmDiagnosticsUnavailableHint": "アラームの設定をまだ確認できていません。"
+  "alarmDiagnosticsUnavailableHint": "アラームの設定をまだ確認できていません。",
+  "autoEqDisableOption": "無効化"
 }