setMapMigrationAssetBrandKit
Point a converted form at a different Brand Kit.
Conversion picks the kit from the destination workspace, which is right for a bulk run and wrong for the one form belonging to a different brand.
Null clears it, falling the form back to the product default. This sets the
revision's brand_kit_id only — a form is branded by the kit it NAMES,
resolved at render, never by a copy of the kit's tokens.
setMapMigrationAssetBrandKit(
asset_id: ID!
brand_kit_id: ID
): MapMigrationAsset!
