Support actions that render Jinja templates

[aplowman]

This includes code in #857, which should be merged soon.

This includes the following changes made in support of new task schemas being developed for Gmsh/MOOSE integration in MatFlow, here:

• Support passing input_files to script/program_data_in. Currently it is only a subset of schema inputs that can be passed.
  • Add script/program_input_files; a list of input_files to pass to the script (via the format specified in script/program_data_in
  • Post-process script/program_data_in to make sure inputs are prefixed by inputs., unless they start with input_files.! This disambiguates the two but still allows specifying inputs without the inputs. prefix, as is currently in use.

Jinja template support:

• initial support
• check TaskSchema validation raises on incompatible schema inputs with respect to the Jinja template (missing and extra)
• render templates to shared submission directory, like for scripts
• support env specifiers within template paths, like for scripts
• support parameters within template paths (and for scripts as well!)
• test Action.get_input_types: check gets Jinja inputs
• test Action.is_input_type_required: check Jinja inputs included