Kernel/File: Fixed file read/write hwtests

Make OpenDirectory fail if the directory doesn't exist

The 3DS allows the user to read from files opened with the Write access modifier, even if he did not specify the Read access modifier.

Open the files in binary mode so that we can prevent CR/LF problems in Windows, where a line-end is replaced by these two bytes instead of just 0xA, this was causing problems with the GetSize test

This is in line with what the hardware itself does.

It does this by splitting the initial directory opening into Directory.Open(), which will return false if a stat fails.
Then, Archive::OpenDirectory will return nullptr, and archive.cpp will return an error code .

Change NULLs to nullptrs.

Resolve doxycomment duplication debate

SVC: Implemented GetThreadId.

Implemented RenameFile and RenameDirectory in FS:USER

Misc minor kernel-related changes.

Use the next_thread_id variable directly.

I believe putting comments in the headers has won by a good margin, with everyone other than me preferring it, so time to enshrine it.

For now threads are using their Handle value as their Id, it should not really cause any problems because Handle values are unique in Citra, but it should be changed. I left a ToDo there because this is not correct behavior as per hardware.

mem_map: Make enum for addresses use u32 as the underlying type

hid_user: Pass by reference with PadButtonPress/PadButtonRelease

CMake: Place all built files in a single folder in MSVC

Add stub for ConvertProcessFromDspDram

PTM_U: Added a stub for GetBatteryLevel & GetBatteryChargeState & GetAdapterState 

Should theoretically push retail stuff further along

Silence a few -Wsign-compare warnings.

AC_U: Added a stub for GetWifiStatus

PTM_U: Implemented the GetShellState function.

Fixed viewport error caused by rounding

Dsp service improvements

CFG:U: Implemented the GetCountryCodeID and GetCountryCodeString

Merge Config::ReadXYZs