Refactor how we pass context down to operators

### What problem does your feature request solve?

Currently this is done by adding parameters to the CLI interface, then passing that through the arguments of several functions.

### Describe the solution you'd like

Maybe some kind of context object that can be added to without having to change the API? Or maybe just writing the `meta.json` file quicker?

### Describe alternatives you've considered

No files or tests are named. Start by tracing how CLI parameters are passed through the operator functions and how the meta.json file is written. Done requires an agreed approach for carrying context without repeatedly changing function APIs, with the affected operator paths verified.

Written by the indexing model from the issue text.