[StaticRuntime] Clean up output references and remove dead code (#52237)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/52237
Redo D26331506 (https://github.com/pytorch/pytorch/commit/4c58be4573dbc9274a9edd57edd0166397141e7b). Get rid of `nodiscard` which broke OSS CI.
- Clean up references of outputs, including Tuples/Lists, by using move semantics
- Clean up references of elements in output Tuples/Lists by adding them to `unmanaged_values_` in MemoryPlanner. Check for corner case of Tuple/List element being inputs.
- Modify unit tests to check for use_counts of outputs
- Clean up dead code. A bit overlap with D25592967, but shouldn't be a problem.
This diff does not try to fix the alias problem with the MemoryPlanner.
Reviewed By: swolchok
Differential Revision: D26432539
fbshipit-source-id: e08990e4066c1ce69ad5274860851d012b7be411
