Add pybindings for bpte and ptd file

[lucylq]

Summary:

1. Overload _load_for_executorch_from_bundled_program to take in ptd file as buffer or file
2. Refactor data loader cases to use the utility functions loader_from_buffer, loader_from_file

Functionality used by sas compiler team

Differential Revision: D83518944

[pytorch-bot]

🔗 Helpful Links

🧪 See artifacts and rendered test results at hud.pytorch.org/pr/pytorch/executorch/14678

• 📄 Preview Python docs built from this PR

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

❌ 1 New Failure, 3 Cancelled Jobs

As of commit 56c838c with merge base 73b3303 ():

NEW FAILURE - The following job has failed:

• pull / test-samsung-models-linux / linux-job (gh)
  RuntimeError: Command docker exec -t c4cf8bf2d372b05958d3efa7ae35eb954dd4d8c8158b417ccd332362b56db68d /exec failed with exit code 1

CANCELLED JOBS - The following jobs were cancelled. Please retry:

• periodic (gh)
• pull / test-binary-size-linux-gcc / linux-job (gh)
  ##[error]The operation was canceled.
• pull / test-setup-linux-gcc / linux-job (gh)
  ##[error]The operation was canceled.

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

[facebook-github-bot]

@lucylq has exported this pull request. If you are a Meta employee, you can view the originating diff in D83518944.

[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.