[3.14] gh-151929: Add pythoninfo commands to Tools/wasm/wasi (#152136) (#152224)

[3.14] gh-151929: Add pythoninfo commands to Tools/wasm/wasi (#152136) (#152224)

* gh-151929: Add pythoninfo commands to Platforms/WASI (#152136)

The "build-python", "build-host" and "build" commands now also run
"pythoninfo-build" and "pythoninfo-host" commands.

If no subcommand is provided, display the help.

GitHub Action "WASI":

* Add "pythoninfo-build" and "pythoninfo-host" commands.
* Remove unused and outdated CROSS_BUILD_PYTHON environment variable.

(cherry picked from commit 7c8163719cd23d41daeaed0b243be45de3e82e05)