Enhanced support for lists, maps, strings

[dlvenable]

Is your feature request related to a problem? Please describe.

We have several related requests for transforming maps and lists. We also have the list_to_map and map_to_list processors. Can we combine them somehow?

Describe the solution you'd like

Create a cohesive processor (or set of processors) for supporting array and map transformations.

Issues

• [x] #3961
• [x] #3962
• [x] #3963
• [x] #3964
• [x] #3965
• [x] #3867

[oeyh]

#3867 also falls under this category.