Add VariantBuilder API for constructing Variant values
Add VariantBuilder API for constructing Variant values: a task in LegoFlow-SWE (Harbor dataset). The parquet-variant crate currently lacks a programmatic way to build binary‑encoded Variant values. Without a builder, users cannot easily create Variant data from scratch – for example, to generate…
The task
The `parquet-variant` crate currently lacks a programmatic way to build binary‑encoded Variant values. Without a builder, users cannot easily create Variant data from scratch – for example, to generate test fixtures, construct arbitrary Variant structures, or serialize data into the Parquet Variant format.
Part of Lego-X/LegoFlow-SWE.