dhis2: expose the underlying request in debug mode

[josephjclark]

dhis2 can be very hard to debug when things go wrong, and there's some uncertainty about what's happening under the hood when calling out to a dhis2 function.

A really useful debugging tool would be to SOMEHOW log the actual HTTP request that gets sent to dhis2.

By the same token, it may be useful to see the actual raw response as well.

Assorted notes

• dhis2 does a lot of work to scrub sensitive values. How can we override that when working in the CLI? Would we want to push the same option to lightning? This would have to be an explicit opt-in designed for debugging
• The request and response may be large and it can be hard to read and manipulate these data structures in stdout. What, if anything, can we do about that?
• What IS the request and response? A JSON object? A curl compatible string?
• Serialisation is a fairly big worry - first off request and response objects have a lot of junk which just clutters the output (right now we get a lot of internal axios noise and circular structures), and secondly any data structures in there which don't serialise well - include stuff like dates or sets - will be lost when we serialize