Migrate Kusto-to-metrics transformer off legacy kusto/data/value types

[mkeesey]

Context

The Kusto-to-metrics transform still depends on legacy github.com/Azure/azure-kusto-go/kusto/data/value wrapper types.

This area does not create Kusto clients or execute queries; it handles the shape of values materialized from old Kusto row iterators.

Files

• transform/kusto_to_metrics.go
• transform/kusto_to_metrics_test.go

Current legacy usage

The transformer handles old typed values in result maps, including:

• value.String
• value.Long
• value.Real
• value.Int
• value.DateTime

It checks Valid flags and converts these wrappers into:

• metric names
• numeric metric values
• timestamps
• label values

Migration considerations

This may be easiest after the ADX exporter row materialization changes, because QueryExecutor.iteratorToRows currently determines what concrete value types enter the transformer.

Acceptance criteria

• Transformer production code no longer imports github.com/Azure/azure-kusto-go/kusto/data/value.
• Tests cover the value shapes produced by the migrated azkustodata query path.
• Invalid/null Kusto value behavior remains explicit and tested.
• Existing plain Go value support remains intact.