[StaticRuntime] Clean up output references and remove dead code (#51991)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/51991
- 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.
(Note: this ignores all push blocking failures!)
Test Plan:
```
buck test //caffe2/benchmarks/static_runtime:static_runtime_cpptest
buck test mode/opt-clang caffe2/caffe2/fb/predictor:ptvsc2_predictor_bench_test
```
Reviewed By: bwasti
Differential Revision: D26333953
fbshipit-source-id: cadc0595ad6ab754c4f1f7a5a3733b2c16b3102f
