Move MiiData to its own namespace and add ChecksummedMiiData (#6824)

* Move mii to own namespace and add checksummed mii data

* Fix compile issues

* Make mii classes trivial and add cast operator

* Fix Android side

* Add new line at the end of files.

* Make miidata a struct and crc16 a u32_be as per switch code.

* Apply suggestions

* Change back crc to u16 and set padding to 0.

src/core/hle/mii.cpp

@@ -0,0 +1,13 @@
+// Copyright 2023 Citra Emulator Project
+// Licensed under GPLv2 or any later version
+// Refer to the license.txt file included.
+
+#include <boost/crc.hpp>
+#include "core/hle/mii.h"
+
+namespace Mii {
+u16 ChecksummedMiiData::CalculateChecksum() {
+    // Calculate the checksum of the selected Mii, see https://www.3dbrew.org/wiki/Mii#Checksum
+    return boost::crc<16, 0x1021, 0, 0, false, false>(this, offsetof(ChecksummedMiiData, crc16));
+}
+} // namespace Mii