dist.accelerate component

[d4l3k]

This is a component that uses HuggingFace's accelerate in a similar manner to torchrun. I haven't tested with a accelerate config.

Fixes #834

Test plan:

pytest torchx/components/test/dist_test.py
scripts/component_integration_tests.py --scheduler local_cwd
torchx run -s local_cwd dist.accelerate -j2x2 --script torchx/examples/apps/compute_world_size/main.py