Add filename generator for sample sheet and preparation file

[ElDeveloper]

Per @mmbryant23's request, it would be helpful if the notebooks pre-populated the filename for sample sheets and prep files (mapping files) using the data available in the notebooks. For example: In the amplicon notebook it should the filename should be something like: yyyymmdd_IL515fBC_806_ProjectName_Plates.txt where the date should be 'today's date'. ProjectName_Plate will be the project name and associated plates, per project (a concatenated value separated by underscores).

My suggestion is to write a function that takes in as inputs all the parameters and produces the filename. This way we can reuse the same function in the different notebooks.

[RodolfoSalido]

bumping this issue because automated sample_sheet name parsing to kickstart qiita demultiplexing jobs would benefit from standardized file names.