Task #8387: Port pulp_file off `BaseDistribution` and onto `Distribution` as the MasterModel - File Support - Pulp

Task #8387

Updated by bmbouter about 3 years ago

pulp_file needs to: 

 1. Swap its inheritance to using `Distribution` instead of `BaseDistribution` 

 2. Ship a migration which moves the data from the `BaseDistribution` master table to the `Distribution` master table. 


 NOTE: while doing this work, the author should also implement https://pulp.plan.io/issues/8384 at the same time.