Analysis does not populate `file_core.file_source`

[hannes-ucsc]

The spec requires Analysis to set the provenance.submitter_id on project-level matrices. The use of provenance.submitter_id was a hack to work around the lack (at the time the spec was written) of a suitable schema property to identify the origin of a file.

We now have file_core.file_source and DCP/2 Analysis should populate it, not only for matrices but in all …_file entities it emits. It should be set to DCP/2 Analysis, one of the valid enum values for that property.

To ensure a smooth transition, Analysis should continue to populate provenance.submitter_id for backwards compatibility.