[WIP] Vectorized struct types

[artjomPlaunov]

WIP, do not review yet; depends on #175 and #179 going in first.

// STRUCT(
//     amounts STRUCT(
//         small DECIMAL(4,2),   -- backed by INT16
//         large DECIMAL(38,2)   -- backed by HUGEINT
//     )
// ) -> BOOLEAN

inputVector, _ := state.GetInputChunk().GetVector(0)
input, _ := duckdb.GetStructView(inputVector)

smallVector, _ := input.Field("amounts", "small")
largeVector, _ := input.Field("amounts", "large")

small, _ := duckdb.GetVectorView[duckdb.DecimalValue](smallVector)
large, _ := duckdb.GetVectorView[duckdb.DecimalValue](largeVector)
result, _ := duckdb.GetVectorWriter[bool](state.GetResultVector())

for row := range input.Len() {
	a, aValid, _ := small.GetValue(row)
	b, bValid, _ := large.GetValue(row)

	if !aValid || !bValid {
		_ = result.SetNull(row)
		continue
	}

	_ = result.Set(row, a.Unscaled == b.Unscaled)
}