Inclusion of `wasm`, `tar.gz` and other ignored files in the hatch `shared-data`

[jtpio]

As noticed in #181 (comment), there seems to be an issue with hatch not picking up the files listed in .gitignore.

As a result, they are not included in the wheel shared-data and cause issues like #177 since some files are missing.

#181 updated the .gitignore to narrow the scope of the ignored files, so they can be included in the wheel correctly.

However this feels a bit error-prone and it would be easy to get back to the same issue by adding new entries to the .gitignore.

Some next steps would be:

• make a standalone repo to reproduce this issue
• open an issue / discussion on https://github.com/pypa/hatch if this is reproducible with the test repo
• add a check on CI here to make sure files are correctly included. Or run a small UI test with the production build of jupyterlite-xeus-python to make sure the kernel can at least without errors