Detect reading from non-indexed JSON documents and store it in a LazyJSONDocument instead of an IndexedJSONDocument.

[nicktobey]

This adds tests that we properly read JSON documents written before the migration to the new indexed JSON storage format. When loading such documents from storage, we should represent them as a LazyJSONDocument instead of an IndexedJSONDocument. This ensures we don't accidentally use the optimized versions of the JSON functions when there aren't any keys in the prolly tree to guide the optimization.

[coffeegoddd]

@nicktobey DOLT

comparing_percentages
100.000000 to 100.000000

version	result	total
0888820	ok	5937457

version	total_tests
0888820	5937457

correctness_percentage
100.0