Support for meson-python

If you have a python project that uses meson as its build backend, then the vscode is not able to find the meson configuration. By default, it is a folder of the form `build/cp`. As the build folder depends on the python version, it is hard to use the `mesonbuild.buildFolder` setting to reliable find it (different devs may use different python versions).

A bit related: https://github.com/mesonbuild/vscode-meson/issues/233 https://github.com/mesonbuild/vscode-meson/issues/74

Start by locating where the vscode-meson extension reads or resolves the mesonbuild.buildFolder setting, then review related issues 233 and 74. The change is done when projects using meson-python can reliably locate the version-specific build/cp folder without requiring each developer to configure it manually.

Written by the indexing model from the issue text.