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

[gino-m]

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