Add partitioner, preprocess, and default passes (#21442)

[metascroy]

Summary:

NativePartitioner claims core ATen ops plus a small non-core opt-in set
(matmul/linear/addmm/sdpa) and preserves them via ops_to_not_decompose.
NativeBackend.preprocess serializes the delegated subgraph and ships constants
through the NamedDataStore by fqn. get_default_passes() runs CSE, view_copy
collapsing, and reinplace as pre-lowering transform passes.

Reviewed By: digantdesai

Differential Revision: D111753291

[pytorch-bot]

🔗 Helpful Links

🧪 See artifacts and rendered test results at hud.pytorch.org/pr/pytorch/executorch/21442

• 📄 Preview Python docs built from this PR

Note: Links to docs will display an error until the docs builds have been completed.

✅ No Failures

As of commit db8fe18 with merge base c6213ae ():
💚 Looks good so far! There are no failures yet. 💚

This comment was automatically generated by Dr. CI and updates every 15 minutes.

[meta-codesync]

@metascroy has exported this pull request. If you are a Meta employee, you can view the originating Diff in D111753291.

[github-actions]

This PR needs a release notes: label

If your change should be included in the release notes (i.e. would users of this library care about this change?), please use a label starting with release notes:. This helps us keep track and include your important work in the next release notes.

To add a label, you can comment to pytorchbot, for example
@pytorchbot label "release notes: none"

For more information, see
https://github.com/pytorch/pytorch/wiki/PyTorch-AutoLabel-Bot#why-categorize-for-release-notes-and-how-does-it-work.

[digantdesai]

Review automatically exported from Phabricator review in Meta.