Make AppIconProvider&NotifIconStyleProvider dumpable

Example dump output:
```
    AppIconProviderImpl:
    ----------------------------------------------------------------------------
    cache information:
      NotifCollectionCache(retainCount = 1, purgeTimeoutMillis = 1000)
      	keys present in cache: 4
      		com.google.android.apps.photos
      		com.google.android.calendar
      		com.google.android.gm
      		com.google.android.googlequicksearchbox
      	cache hit ratio = 88.2353% (30 hits, 4 misses)
    icon factory information:
      fullResIconDpi = 360
      iconSize = 108

    NORMAL dump took 1ms -- AppIconProviderImpl

    NotificationIconStyleProviderImpl:
    ----------------------------------------------------------------------------
    cache information:
      NotifCollectionCache(retainCount = 1, purgeTimeoutMillis = 1000)
      	keys present in cache: 5
      		android
      		com.google.android.apps.photos
      		com.google.android.calendar
      		com.google.android.gm
      		com.google.android.googlequicksearchbox
      	cache hit ratio = 86.84211% (33 hits, 5 misses)

    NORMAL dump took 1ms -- NotificationIconStyleProviderImpl

    Dump took 5ms
```

Bug: 371174789
Test: adb shell dumpsys activity service com.android.systemui/.SystemUIService AppIconProviderImpl NotificationIconStyleProviderImpl
Flag: android.app.notifications_redesign_app_icons
Change-Id: Ia9f98af84026440c5483bf100bee4352924f37af