Find some generic formatting, transformation, DSL, filtering, scripty language to embed in the yaml and run on the data

[alexkreidler]

• python
• filtery dsl
• Go filters on native data aren't great
• some DSL which is frontend to the Apache Arrow/FoundationDB ETL layer

Processor API extensibility/chaining/merging
Use multiple ProcAPIs -- e.g. use the regular executor one, but an additional special one for the ETL layer -- all kernels exposed as processors with their own configs etc