bump cutlass to 3.8

[kushanam]

Bumping CUTLASS to 3.8 and updating the make file for Blackwell arch

[LucasWilkinson]

Apologies for the inconvenience! But, this repo had diverged pretty far from upstream so we've been in a slow moving repo reset (I.e. starting a new branch from upstream) since it was untenable to rebase/sync with upstream. The "main" branch that was being used for the past couple weeks was not actually main, the branches have now been renamed to reflect there roles, can you please update this PR to point to the new main (the old main is now main-archive).

Some pointers for updating your local env

git branch -m lwilkinson/fa3-squashed main
git fetch origin
git branch -u origin/main main
git remote set-head origin -a