Same to psutil and analogs it is expected to have some method to retrieve information about process owner. It seems reasonable to return heim::host::User instead of plain username, as it will allow to get rich information about owner.

Due to current project structure, heim-host sub-crate probably should be extended with method like User::get(uid), which will be utilized by heim-process later.

Points:

• Check what info about owner can be obtained from the process on all platforms supported (uid preferably)
• Check if we are able to make User::get happen
• Add async fn Process::owner method (or should it be Process::user? Discussable)