This replaces the `__getattr__()` pattern used in remaining OpHandlers with a `DefaultHandler` class defined in part 2.
Some compile time wins from this as well:
```
2025-02-02T19:46:32.2033010Z
2025-02-02T19:46:32.2036607Z WIN: benchmark ('add_loop_inductor', 'compile_time_instruction_count') failed, actual result 29633182927 is -1.71% lower than expected 30150000000 ±1.50% please update the expected results.
2025-02-02T19:46:32.2037575Z
2025-02-02T19:46:32.2037907Z please update all results that changed significantly, and not only the failed ones
2025-02-02T19:46:32.2039291Z PASS: benchmark ('add_loop_inductor_dynamic_gpu', 'compile_time_instruction_count') pass, actual result 43986879172 -1.02% is within expected 44440000000 ±2.50%
2025-02-02T19:46:32.2040131Z
2025-02-02T19:46:32.2041180Z WIN: benchmark ('add_loop_inductor_gpu', 'compile_time_instruction_count') failed, actual result 26246225695 is -1.85% lower than expected 26740000000 ±1.50% please update the expected results.
2025-02-02T19:46:32.2042188Z
```
Pull Request resolved: https://github.com/pytorch/pytorch/pull/146255
Approved by: https://github.com/shunting314
ghstack dependencies: #146252, #146254
Note [TH abstraction violation]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
TH/THC provide some hpp headers, which are proper C++ headers rather than
C headers. These headers serve double duty as *internal implementation
detail* headers, whose contents should largely not be used by external
clients.
Ideally, we would not install these headers at all; instead, you should
use public functions (in headers like `THTensor.h`, NOT `THTensor.hpp`)
to manipulate these structs. However, there are a few places
in torch/csrc where we violate this abstraction. They are marked with
a pointer to this note. Each of those sites will have to be refactored
when we refactor the guts of THTensor and related structures.
403db2faee