[Code health] Invert control of data collection flow view models

Currently, the container's view model (`DataCollectionViewModel`) is responsible for creating and managing the view models of the children tasks. Since these are passed through the constructor, this makes it impossible to restore the view on config change (#2725). Instead, child fragments need to get their own vms, probably from the parent fragment.

@shobhitagarwal1612 @scolsen @anandwana001