API docs: Go iota are not grouped logically

[emidoots]

From Noah:

Godoc groups iota-based named types under the same type, while iota-based untyped numbers are part of the Constants group. Where theyre located is relatively minor compared to showing them together, see pic 2 and 3

[emidoots]

I took a look at this for a few hours, but it's unfortunately much harder to do in practice than I thought.

We could easily "just" replicate what godoc does here - but it's annoying for a few reasons:

1. If we replicate what godoc does, then each const/var is not a distinct section. That means we can't easily go from a hover tooltip -> API docs or vice-versa (at least not in the near term, we can if we get bi-directional linking of documentationResult detail strings <-> result sets.
2. If we emit them as separate sections, we can't easily present them together more closely.
3. If we try to nest them underneath their parent type:
   a. They are not always typed (e.g. http status codes are not typed except as int)
   b. They'd still be separated

I think this is doable, but we'll want to directly replicate what godoc does and deal with the complexity of the bi-directional linking within documentationResult detail strings so that we can still go-to-definition etc both directions.