Introduce public MergedDataMap

[lucylq]

Summary:
Add public merged data map. Module can use this to resolve multiple named data maps.
Creating as a sep dependency rather than inside module/ so it can be used independently of module. (think there may be some other internal usages soon)

Add support for BUCK and CMake. On CMake side, have to add the dep for everyone who uses module ..

Reviewed By: swolchok

Differential Revision: D83527299

[pytorch-bot]

🔗 Helpful Links

🧪 See artifacts and rendered test results at hud.pytorch.org/pr/pytorch/executorch/14861

• 📄 Preview Python docs built from this PR

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

❗ 1 Active SEVs

There are 1 currently active SEVs. If your PR is affected, please view them below:

• An error occurred (AccessDenied) when calling the ... operation

❌ 1 New Failure

As of commit 64b0045 with merge base 0bfb61e ():

NEW FAILURE - The following job has failed:

• pull / test-samsung-models-linux / linux-job (gh)
  RuntimeError: Command docker exec -t 1455ed26a2e867c15b3db349a4d764f8ba8c367b4e994658c6cc83bc74c16af8 /exec failed with exit code 1

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

[meta-codesync]

@lucylq has exported this pull request. If you are a Meta employee, you can view the originating Diff in D83527299.

[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.

[swolchok]

Review automatically exported from Phabricator review in Meta.