Replaces `std::shared_pointer` with `stx::atomic_ptr` and `stx::shared_ptr`.
Notes to programmers:
* This pr kills the use of `dynamic_cast`, `std::dynamic_pointer_cast` and `std::weak_ptr` on IDM objects, possible replacement is to save the object ID on the base object, then use idm::check/get_unlocked to the destination type via the saved ID which may be null. Null pointer check is how you can tell type mismatch (as dynamic cast) or object destruction (as weak_ptr locking).
* Double-inheritance on IDM objects should be used with care, `stx::shared_ptr` does not support constant-evaluated pointer offsetting to parent/child type.
* `idm::check/get_unlocked` can now be used anywhere.
Misc fixes:
* Fixes some segfaults with RPCN with interaction with IDM.
* Fix deadlocks in access violation handler due locking recursion.
* Fixes race condition in process exit-spawn on memory containers read.
* Fix bug that theoretically can prevent RPCS3 from booting - fix `id_manager::typeinfo` comparison to compare members instead of `memcmp` which can fail spuriously on padding bytes.
* Ensure all IDM inherited types of base, either has `id_base` or `id_type` defined locally, this allows to make getters such as `idm::get_unlocked<lv2_socket, lv2_socket_raw>()` which were broken before. (requires save-states invalidation)
* Removes broken operator[] overload of `stx::shared_ptr` and `stx::single_ptr` for non-array types.
* Fix /dev_flash executables path arg. (/host_root is wrong for it)
* Fix usage of /host_root for homebrew applications when it is not mounted, use /app_home.
* Fix path source detection. (don't get fooled by path slashes repetitions, symlinks, '.', ".." and ('\' on Windows))
* Unescape tail of /dev_hdd0 paths.
Properly handle . and .. path components in mountpoint detection.
Remove app_home mountpoint and use mountpoint from argv[0] instead.
Add dev_root mountpoint for special purposes.
