[dtensor][4/n] don't use make_fx for strategy propagation (#108262)
We were using make_fx for strategy based propagation so that we can get
a graph and the shape related metadata, this becomes too much overkill
for the sharding propagation purpose. This change refactors the strategy
propagation to remove the graph based propagation, instead just use the
op to index to the strategy functions.
We also just use a fake shape prop instead of relying on fx tracing for
the shape/stride propagation.
for a future possible decomposed propagation, we will exercise different
codepath to enable that
NOTE that this would also greatly reduce the latency of:
1. first time dtensor operations when populating the cache, the first
iter would become faster again!
2. greatly reduce the test_dtensor_ops.py time again, right now the
whole test finished within 2-3 mins again.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/108262
Approved by: https://github.com/fduwjj
ghstack dependencies: #107306, #108261
