[FEA]: Add support for CU_LAUNCH_ATTRIBUTE_PROGRAMMATIC_EVENT in LaunchConfig

[lijinf2]

Is this a duplicate?

• I confirmed there appear to be no duplicate issues for this request and that I agree to the Code of Conduct

Area

cuda.core

Is your feature request related to a problem? Please describe.

LaunchConfig does not expose CU_LAUNCH_ATTRIBUTE_PROGRAMMATIC_EVENT, which records a programmatic event for cross-stream PDL (complements same-stream programmatic_stream_serialization from #1334).

Parent tracking: #496.

Describe the solution you'd like

• Users can set CU_LAUNCH_ATTRIBUTE_PROGRAMMATIC_EVENT via LaunchConfig.
• Mapping to the native launch attribute is tested.

Describe alternatives you've considered

Use cuda.bindings.driver (CUlaunchAttribute / CU_LAUNCH_ATTRIBUTE_PROGRAMMATIC_EVENT) and cuLaunchKernelEx directly.

Downside: leaves cuda.core users without a first-class LaunchConfig API; they must drop to low-level bindings, manage the attribute array themselves, and lose consistency with other LaunchConfig launch attributes (programmatic_stream_serialization, etc.).

Additional context

Incremental LaunchConfig attribute coverage under #496 (same approach as #1334 for programmatic_stream_serialization).

No example code in the design notes for this attribute.