Fix EnRouteView expand button not expanding issue.

The id of the top view needs to be
@*android:id/status_bar_latest_event_content. This is because
NotificationViewWrapper.wrap() uses `v.getId() ==
com.android.internal.R.id.status_bar_latest_event_content` when deciding
which wrapper to use. We need NotificationTemplateViewWrapper here
(instead of NotificationViewWrapper) for the expand button to work,
among other things.

Note that this means the same id is used twice in the view hierarchy.
This seems to be working fine given how these ids are used currently.

Added an initial expanded layout (copied from the big_base layout) for
testing the expand button.

Flag: android.app.api_rich_ongoing
Flag: com.android.systemui.notification_row_content_binder_refactor
Bug: 343942780
Bug: 359128724
Bug: 359920094
Test: EnRouteViewModelTest
Test: Trigger example EnRouteStyle notification on device
Change-Id: I6b3f7af1b7fbf0e48db2cf1ab3fa6415ffeb47f2