Add OPN instruction and vararg operator table (#27104)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/27104
* The use case here is to replace prim::ListConstruct, which requires Node, but Node is not available in mobile lite interpreter.
* (OPN, X, N), X is the index to the vararg operator-name and operator tables. N is number of inputs. For ListConstruct example, operator name can be "aten::listconstruct" and the overloaded name is the output type ("int", "float", "bool", "tensor" and "generic").
* A vararg operator table is built with void(int input_size, Stack& stack) functions.
## Unit test
LiteInterpreterConv covers OPN instruction and conv operator.
Test Plan: Imported from OSS
Differential Revision: D17762853
fbshipit-source-id: 475aa0c6678e3760cec805862a78510913a89c83
