Support best-effort JSON parser

[lowell80]

Add best-effort JSON parsing support to the nested JSON parsing function. It looks like the ijson package may do this, but I haven't tested it. The use case for this functionality is the fact that some nested JSON payloads appear to be subjected to size constraints.

This happens in MS Office 365 Management logs, for example. We should parse whatever we can (best effort) so that some of the data can be retrieved, instead of discarding all of it. I think this lines up with spaths general best-effort approach.