Skip TopKind in maps

[spinillos]

I was testing v0.1.3 with our current cue files and I saw the following:

panels: [...(#Panel | #GraphPanel | #HeatmapPanel)] @grafanamaturity(NeedsExpertReview)

was generating:

panels?: Array<(Panel | RowPanel | {
    type: 'graph';
  } | {
    type: 'heatmap';
})>;

with 0.1.3:

panels?: Array<(Panel | Record<string, unknown> | Record<string, unknown>)>;

And its not right.

The issue came because GraphPanel and HeatmapPanel are structs with data like:

#Something: {
  foo: "bar"
  ...
}

These structs are detected as maps, their kind is cue.TopKind and we set unknown. So if we skip them, we can generate the proper value without losing information.

Note: I back any as default in TopKind kind. When we detect an empty {...} the writer is going to print Result<string, unknown> like it was doing before.