TiledMLP support for FSDP2 (#2950)

* make TiledMLP work with FSDP

* cleanup/gc at start of train to prevent large VRAM spike

* chore: lint

* generic function for non-deepspeed training

* unify patch to fix imports

* update readme for ALST and add examples

* make deepspeed attribute on params check more robust

* update with new info from PR review

examples/alst/README.md

@@ -0,0 +1,9 @@
+# Arctic Long Sequence Training (ALST)
+
+Artic Long Sequence Training (ALST) is a technique for training long context models using a variety of optimization
+techniques. It is a combination of:
+- TiledMLP: Leverage tiling over the sequence dimension on MLP layers to reduce memory usage
+- Tiled Loss: Using optimized loss functions like Liger-Kernel or Cut Cross Entropy to reduce memory usage
+- Activation Offloading: Offload activations to CPU RAM to reduce memory usage
+
+For more information, you can check out the ALST paper [here](https://www.arxiv.org/abs/2506.13996).