docs: add new quickstart for job launching

[d4l3k]

This updates the README/index/quickstart to highlight the job launching as the main user entrypoint as per https://docs.google.com/document/d/14icG0GJG1nPHF3DW7yMreZpe3S8FwYdrI_XYIzDTSbI/edit

Changes:

• update README/index w/ new job launcher descriptions emphasized
• move existing quickstart to custom_compents.md
• update utils.python to have --script to match dist.ddp
• update the pipelines/scheduler doc pages to list all child schedulers via glob
• make pipeline doc structure match scheduler doc (piplines/, schedulers/)
• docker_workspace
  • use Dockerfile.torchx to avoid unexpected collisions with Dockerfile.
  • docker_workspace pull images explicitly to avoid error from newer docker daemon during build
• docker_scheduler: skip pulling sha256: images to avoid logspam

Test plan:

cd docs; make clean html
pyre

CI

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@d4l3k has updated the pull request. You must reimport the pull request before landing.

[facebook-github-bot]

@d4l3k has imported this pull request. If you are a Meta employee, you can view this diff on Phabricator.

[facebook-github-bot]

@d4l3k has updated the pull request. You must reimport the pull request before landing.

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@d4l3k has imported this pull request. If you are a Meta employee, you can view this diff on Phabricator.

[codecov]

Codecov Report

Merging #404 (bddc9e7) into main (571fd78) will decrease coverage by 0.32%.
The diff coverage is 35.29%.

@@            Coverage Diff             @@
##             main     #404      +/-   ##
==========================================
- Coverage   94.54%   94.21%   -0.33%     
==========================================
  Files          66       66              
  Lines        3664     3681      +17     
==========================================
+ Hits         3464     3468       +4     
- Misses        200      213      +13     

Impacted Files	Coverage Δ
torchx/components/utils.py	51.72% <0.00%> (-8.28%)	⬇️
torchx/workspace/docker_workspace.py	93.57% <66.66%> (-1.62%)	⬇️
torchx/schedulers/docker_scheduler.py	96.13% <100.00%> (-1.08%)	⬇️
torchx/schedulers/aws_batch_scheduler.py	82.79% <0.00%> (-2.60%)	⬇️
torchx/schedulers/kubernetes_scheduler.py	92.67% <0.00%> (ø)
torchx/components/dist.py	79.06% <0.00%> (+1.29%)	⬆️

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