Support for mi_process_info()

[rohitjoshi]

mimalloc provides apis retrieve process information .e.g. rss, commit_size etc. Can you please make this api available?

process info:

mi_decl_export void mi_process_info(size_t* elapsed_msecs, size_t* user_msecs, size_t* system_msecs, 
                                    size_t* current_rss, size_t* peak_rss, 
                                    size_t* current_commit, size_t* peak_commit, size_t* page_faults) mi_attr_noexcept;