Reorganize some logic within NotificationRowContentBinderImpl

* beginInflationAsync is a new method that wraps createRemoteViews
* createRemoteViews *only* creates a NewRemoteViews object that holds the RemoteViews for each state
* ConversationNotificationProcessor is now called within beginInflationAsync instead of in that method's callers
* SingleLineViewModel is created inside beginInflationAsync instead of in that method's callers

Bug: 343942780
Flag: com.android.systemui.notification_row_content_binder_refactor
Test: atest NotificationRowContentBinderImplTest
Change-Id: I24f9e6dd6dc27deb8c1b9b5ee47e9483e56ff45b