Tracking issue: `std::filesystem::path` headaches, and breakage on Windows with non-ASCII paths

### Version v24.1.0 ### Platform ```text Microsoft Windows NT 10.0.19045.0 x64 ``` ### Subsystem _No response_ ### What steps will reproduce the bug? Couldn't find a tracking issue for this one. There are places in the source that handle `std::filesystem::path` objects, and on Windows, this involves conversion between UTF-8 strings and wchar-based `path`s. This can lead to path corruption, as previously discussed. One example of this is #56049, which has an open PR to fix this specific usage. However, #58764 has just been reported, which affects a completely different area of the API. There are other examples of usage elsewhere in the source. It feels like this probably needs a library-wide approach – even if not removing `std::filesystem::path` entirely as previously discussed, then at least some sort of internal wrapper API to abstract out potential footguns.