Root Object Draft

[Hydrocharged]

This adds root objects, which Doltgres uses to implement sequences (for now). They're flexible enough that they're also usable for other things that we may want to put on the root, while making such changes Doltgres-only changes.

This is a similar approach to ExtendedTypes allowing us to handle all type information, serialization, etc. from the Doltgres layer.

[Hydrocharged]

Ignore failed tests for now.

[coffeegoddd]

@Hydrocharged DOLT

comparing_percentages
100.000000 to 100.000000

version	result	total
6d0e485	ok	5937457

version	total_tests
6d0e485	5937457

correctness_percentage
100.0