Generate sdist by hand

[tomjakubowski]

This updates the perspective-python build to create an sdist tarball by
hand, not going through maturin sdist. This bypasses some issues we
have seen with Maturin mispackaging the perspective Cargo workspace in
the sdist.

Maturin is still used as the build-backend to build a wheel from the
sdist. CI still uses maturin build to build wheels. Local
development builds still use maturin develop.

The sdist now includes the .data directory so that Maturin will place it
in the wheel correctly. Building an sdist with PSP_BUILD_SDIST=1 will
now error if it appears the jupyterlab plugin was not built into the
.data directory.

Most of the work is in generating a PKG-INFO file. Its output matches
what's in the 3.1.2 sdist on pypi, minus a correction to fix the
Home-page field miscapitalized by Maturin and some unimportant
whitespace changes in Require-Dist.

Pull Request Checklist

• Description which clearly states what problems the PR solves.
• Description contains a link to the Github Issue, and any relevent
  Discussions, this PR applies to. (N/A)
• Include new tests that fail without this PR but passes with it.
• Include any relevent Documentation changes related to this change.
• Verify all commits have been signed in accordance with the DCO policy.
• Reviewed PR commit history to remove unnecessary changes.
• Make sure your PR passes build, test and lint steps completely.

[tomjakubowski]

test_js failure looks familiar, I think it's a known flaky test

In the sdist artifact, looks like the labextension is packaged as expected (just the one copy):

~/Downloads › tar tzvf perspective_python-3.1.2.tar.gz | grep labextension
-rw-r--r--  0 1001   127       203 Oct 28 14:34 perspective_python-3.1.2/perspective/labextension/install.json
-rw-r--r--  0 1001   127      2513 Oct 28 14:34 perspective_python-3.1.2/perspective/labextension/package.json
-rw-r--r--  0 1001   127   5073815 Oct 28 14:34 perspective_python-3.1.2/perspective/labextension/static/253.33663433de87e488ba09.js
-rw-r--r--  0 1001   127      2452 Oct 28 14:34 perspective_python-3.1.2/perspective/labextension/static/253.33663433de87e488ba09.js.LICENSE.txt
-rw-r--r--  0 1001   127    105550 Oct 28 14:34 perspective_python-3.1.2/perspective/labextension/static/295.b558c522e11647489867.js
-rw-r--r--  0 1001   127      8860 Oct 28 14:34 perspective_python-3.1.2/perspective/labextension/static/remoteEntry.1b5e905e1f26c06be4dd.js
-rw-r--r--  0 1001   127       193 Oct 28 14:34 perspective_python-3.1.2/perspective/labextension/static/style.js
-rw-r--r--  0 1001   127      2453 Oct 28 14:34 perspective_python-3.1.2/perspective/labextension/static/third-party-licenses.json
~/Downloads › tar tzvf perspective_python-3.1.2.tar.gz | grep remoteEntry
-rw-r--r--  0 1001   127      8860 Oct 28 14:34 perspective_python-3.1.2/perspective/labextension/static/remoteEntry.1b5e905e1f26c06be4dd.js

And the wheel artifact still has the one copy of the labextension, in the .data directory, as expected

[tomjakubowski]

there may be pitfalls in doing it this way I'm not aware of, but it seemed less messy than patching the Cargo.toml file in the tarball.

[tomjakubowski]

Did a manual run in my oneoffs repo to verify that the sdist installs on macOS/aarch64: https://github.com/tomjakubowski/perspective-oneoff-tests/actions/runs/11584975281

I think we probably want at least the option to test in CI that (1) installs from the sdist (2) runs the pytest test suite on the installed package (3) verifies that the labextension is listed in jupyter labextension list. Maybe a manual-only (workflow_dispatch) workflow, or one which runs only on release tags? I'll plug away at something like that.

[tomjakubowski]

Another CI job with a diff of the sdist from this branch compared to the 3.1.2 sdist on pypi: https://github.com/tomjakubowski/perspective-oneoff-tests/actions/runs/11585843746/job/32255425110

link to diff artifact https://github.com/tomjakubowski/perspective-oneoff-tests/actions/runs/11585843746/artifacts/2120979686

One thing that stood out is that the sdist has lost the release profile flags from the workspace root's Cargo.toml. May want to add those back