Rewrite/simplify dataset reinstaller.

[Foxcapades]

Right now the data-install lane already attempts to install datasets that are in the ready-for-reinstall status. The dataset reinstaller also attempts to install datasets that are in the ready-for-reinstall status.

I suggest that we clarify and simplify the dataset reinstallation process by doing the following:

1. Add a new InstallStatus enum member ready-for-cleanup which will indicate to the dataset-reinstaller that the dataset is able to be cleaned up and reinstalled
2. Alter the dataset-reinstaller to:
   a. Uninstall datasets in the ready-for-cleanup status
   b. Mark uninstalled datasets as ready-for-reinstall
   c. Fire install events for the uninstalled datasets

This will remove the duplicated dataset installation logic and clarify the usages of the ready-for-reinstall status which is currently overloaded.