Fix build isolation and editable install issues

[larryliu0820]

Summary:
This PR fixes two issues affecting the build and installation process:

1. pyproject.toml configuration: Fixed invalid license and license-files fields that were causing build failures with newer versions of setuptools and pip build isolation. The license field now uses the table format {text = ...} and license-files was moved to [tool.setuptools].

2. Editable install version.py: Fixed an issue where version.py was being written to the project root instead of the package directory (src/executorch) during editable installs. This was causing ImportError: cannot import name 'version' when importing executorch.

Test Plan:

• Verified pip install . --no-build-isolation works (metadata generation succeeds).
• Verified pip install -e . --no-build-isolation works and from executorch import version succeeds.

Summary

[PLEASE REMOVE] See CONTRIBUTING.md's Pull Requests for ExecuTorch PR guidelines.

[PLEASE REMOVE] If this PR closes an issue, please add a Fixes #<issue-id> line.

[PLEASE REMOVE] If this PR introduces a fix or feature that should be the upcoming release notes, please add a "Release notes: " label. For a list of available release notes labels, check out CONTRIBUTING.md's Pull Requests.

Test plan

[PLEASE REMOVE] How did you test this PR? Please write down any manual commands you used and note down tests that you have written if applicable.

cc @GregoryComer

[pytorch-bot]

🔗 Helpful Links

🧪 See artifacts and rendered test results at hud.pytorch.org/pr/pytorch/executorch/15941

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❌ 1 New Failure, 1 Pending

As of commit bd35c44 with merge base 23fc78f ():

NEW FAILURE - The following job has failed:

• pull / android / run-emulator (gh)
  The process '/usr/bin/sh' failed with exit code 1

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

[abhinaykukkadapu]

Curious, is this the symlinked folder or the actual source folder?

[larryliu0820]

the one under src/, so src/executorch

[abhinaykukkadapu]

Seems like tests are failing to build the package with the change.

[larryliu0820]

I just rebased, let's see

[mergennachin]

It would be good to validate whether the new format in your PR is compatible with 77.0.3

[larryliu0820]

It would be good to validate whether the new format in your PR is compatible with 77.0.3

Oh I think v75.8.0 is the version with this error:

(executorch) larryliu@larryliu-mac executorch % pip install . --no-build-isolation
Processing /Users/larryliu/executorch
  Preparing metadata (pyproject.toml) ... error
  error: subprocess-exited-with-error
  
  × Preparing metadata (pyproject.toml) did not run successfully.
  │ exit code: 1
  ╰─> [38 lines of output]
      Traceback (most recent call last):
        File "/Users/larryliu/miniconda3/lib/python3.12/site-packages/pip/_vendor/pyproject_hooks/_in_process/_in_process.py", line 389, in <module>
          main()
        File "/Users/larryliu/miniconda3/lib/python3.12/site-packages/pip/_vendor/pyproject_hooks/_in_process/_in_process.py", line 373, in main
          json_out["return_val"] = hook(**hook_input["kwargs"])
                                   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
        File "/Users/larryliu/miniconda3/lib/python3.12/site-packages/pip/_vendor/pyproject_hooks/_in_process/_in_process.py", line 175, in prepare_metadata_for_build_wheel
          return hook(metadata_directory, config_settings)
                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
        File "/Users/larryliu/miniconda3/lib/python3.12/site-packages/setuptools/build_meta.py", line 377, in prepare_metadata_for_build_wheel
          self.run_setup()
        File "/Users/larryliu/miniconda3/lib/python3.12/site-packages/setuptools/build_meta.py", line 320, in run_setup
          exec(code, locals())
        File "<string>", line 777, in <module>
        File "/Users/larryliu/miniconda3/lib/python3.12/site-packages/setuptools/__init__.py", line 117, in setup
          return distutils.core.setup(**attrs)
                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
        File "/Users/larryliu/miniconda3/lib/python3.12/site-packages/setuptools/_distutils/core.py", line 160, in setup
          dist.parse_config_files()
        File "/Users/larryliu/miniconda3/lib/python3.12/site-packages/setuptools/dist.py", line 652, in parse_config_files
          pyprojecttoml.apply_configuration(self, filename, ignore_option_errors)
        File "/Users/larryliu/miniconda3/lib/python3.12/site-packages/setuptools/config/pyprojecttoml.py", line 72, in apply_configuration
          config = read_configuration(filepath, True, ignore_option_errors, dist)
                   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
        File "/Users/larryliu/miniconda3/lib/python3.12/site-packages/setuptools/config/pyprojecttoml.py", line 140, in read_configuration
          validate(subset, filepath)
        File "/Users/larryliu/miniconda3/lib/python3.12/site-packages/setuptools/config/pyprojecttoml.py", line 61, in validate
          raise ValueError(f"{error}\n{summary}") from None
      ValueError: invalid pyproject.toml config: `project.license`.
      configuration error: `project.license` must be valid exactly by one definition (2 matches found):
      
          - keys:
              'file': {type: string}
            required: ['file']
          - keys:
              'text': {type: string}
            required: ['text']
      
      [end of output]
  
  note: This error originates from a subprocess, and is likely not a problem with pip.
error: metadata-generation-failed

× Encountered error while generating package metadata.
╰─> See above for output.

note: This is an issue with the package mentioned above, not pip.
hint: See above for details.

v77.0.3 works well.

v80.9.0 works well.