Mark pywavemap as a typed extension and address cpplint v2.0 warnings

[victorreijgwart]

Description

This PR adds a py.typed marker file to indicate that the pywavemap package comes with type annotations. It also addresses warnings about missing includes for STL header files generated by the new version of cpplint.

Many thanks to @Divelix for implementing it!

Type of change

• New feature

Detailed summary

Indicating that pywavemap comes with type annotations is useful as it allows mypy, and IDEs like VSCode, to automatically detect potential issues and provide better autocompletions. For more information on py.typed files, see PEP 561. We generate the file using nanobind's CMake interface.

Regarding cpplint, we were until recently using version 1.6.1, which only detected missing includes for STL headers up to C++11. Among other improvements, version 2.0.0 also significantly increases its include-what-you-use check coverage -- especially new C++17 STL headers. This PR addresses all these new warnings.

Checklist:

• My code follows the style guidelines of this project
• I have performed a self-review of my code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• Any required changes in dependencies have been committed and pushed

[LionelOtt]

Looks good to me, though probably in the future it may make sense to have different things as different PR, like linter and nanobind stuff here. Though obviously I can see with the nanobind thing being a single line it may look at bit silly :-)

[victorreijgwart]

Thanks for reviewing @LionelOtt! I agree these changes should have been separate. They mainly got tangled because I didn't pin the version of cpplint used in CI, and its version 2 got released in between wavemap v2.1.0 and this PR. So I addressed its warnings to get CI to pass.

I'll add a TODO to pin the versions for all the tools we use, both in CI and in the install script we provide to set up local dev environments.