[Static Runtime] Group graph nodes into input aliases & output aliases (#65517)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/65517
This change retrofits `GetAlwaysAliveValues` into `ValueGroup` to group the values used by a graph into three groups as follows:
- input_aliases: values that are either inputs or contain aliases of inputs or constants.
- output_aliases: values that are either outputs or contain aliases of outputs and are not in input_aliases.
- Values that dont't show up in input_aliases and output_aliases are internally created consumed within the graph.
`output_aliases` is the only new group introduced by this change, and a following diff will use this to preallocate output Tensors to accelerate Static Runtime's performance.
Test Plan: Added `ValueGroup.Init` to cover the updated code path. Note that there was no test for `GetAlwaysAliveValues` before.
Reviewed By: hlu1
Differential Revision: D30940955
fbshipit-source-id: 2cb065ecda0f447a61e64a7cf70cc7c6947f7dfc
