[GRA-258] Pressing run on an existing run with a RunFile fails

[edlouth]

To reproduce:

1. Add a source which uses a file, for example dbt or yaml file.
2. You should get a screen showing the run, as the file is processed.
3. On this screen press the Run button and you will get an error.

The bug relates to the fact that the file is associated with an individual run, as a RunFile Django model. Pressing the button causes a new Run to be created, but it isn't associated with the file. The solution is to copy the file and create a new RunFile for the new Run.

_{From SyncLinear.com | GRA-258}