Consolidate Upload / ETL / Receive

[aeberhart]

The platform currently offers three ways to load data:

	Upload	Receive	ETL
Parameter	CSV, XLSX, ...	JSON	---
Mapping	can only specify datatype and pk column	full jsonata mapping	full jsonata mapping
Upload UI	yes	no	no
Streaming support	no	no	yes

It would be nice to have the following possibilities:

• for a Receive function, instead of just allowing JSON samples, we could offer uploading a file in base64
• Receive could offer a function to convert / map the input
• offer versions of openCSV, etc. that work on in memory files encoded as base64 - this would allow uploading files via forms, passing them as base64, parsing them via JSONata and processing them further
• the run function button should allow specifying parameters

[aeberhart]

Receive is supposed to serve IoT scenarios, where DJ serves as a data sink. Therefore, there's no need to extend it to a full blown data upload UI. It is sufficient, to implement $parseCsv etc. This also allows the Receive function to process CSV that is passed as a JSON string