[FSDP] Add always_wrap policy (#73687)
Summary:
Add a smaller helper policy that always returns True to automatically always wrap all FSDP submodules. This is the first and simplest step of providing a set of policies that allow users to seamlessly experiment with different FSDP config.
More Context: https://github.com/pytorch/pytorch/issues/68789
Pull Request resolved: https://github.com/pytorch/pytorch/pull/73687
Reviewed By: jbschlosser, zhaojuanmao
Differential Revision: D34625801
Pulled By: rohan-varma
fbshipit-source-id: f20c951f8d62ea29b504543c93acd546247d8206
(cherry picked from commit 3b0bf02bc8bb236ee09e2fa986d52bbf5231efc3)
