Move V-Pipe specific functions into sr2slio

[gordonkoehn]

Functions such as sample_id_decoder, batch_id_decoder, get_metadata can be part of sr2silo main because we have decided that this package will be specific for this import.

This should be part of a special call called

vpipe.metadata

[gordonkoehn]

Move it all into a silo module now.

Next step it to make this into an object we call sample where it assigned itself all the metadata