Isolate Icon loader on Android

https://github.com/mozilla-mobile/android-components/blob/v44.0.1/components/browser/icons/src/main/java/mozilla/components/browser/icons/BrowserIcons.kt#L89

And what's DataUriIconLoader?

Coming from https://github.com/mozilla-mobile/android-components/blob/v44.0.1/components/feature/webnotifications/src/main/java/mozilla/components/feature/webnotifications/NativeNotificationBridge.kt#L68