Refactor `OperatorSupport` related code and fix TRT not supporting int64 dtype (#65848)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/65848
This diff includes:
* [fix]: The initialization of `OperatorSupport._support_dict` makes it a class variable, so we need to move its initialization into constructor.
* Add abstract class (more of an interface) `OperatorSupportBase`, since `OperatorSupport`'s purpose is too specific.
* [refactor]: what `TRToperatorSupport` really does is to populate a `OperatorSupport._support_dict`, so there really is no reason for subclassing. So removing it, and changing it to instantiating a `OperatorSupport` with properly populated `_support_dict`.
* Add a framework for defining simple and basic op support logic, and composing them into more complex ones:
1. `create_op_support` wraps a function into a `OperatorSupportBase` instance
2. `chain` can combine several simple `OperatorSupportBase` into more complex ones
3. `OpSupports` provides a set of pre-defined, simple `OperatorSupportBase` that can be composed together using `chain`.
1. Currently the only pre-defined one is `decline_if_input_dtype(..)`, which declares a node non-supported, if its args are of user specified dtype
* Fix `TRTOperatorSupport` so that it not only looks for registered converters, but also decline a node if its arg is of int64
Test Plan: linter and CI
Reviewed By: 842974287
Differential Revision: D31275525
fbshipit-source-id: bbc02f7ccf4902a7912bb98ba5be2c2fbd53b606
