ScanDirectoryTreeAndCallback, before this change, coupled error/return
codes and actual return values (number of entries found). This caused
confusion and difficulty interpreting the precise way the function
worked.

Supersedes, and closes #1255.

Converted FileUtil::ScanDirectoryTree and FileUtil::DeleteDirRecursively
to use the new ScanDirectoryTreeAndCallback function internally.

Each archive now takes a mount point of either NAND or SDMC, and builds its own directory structure there, trying to simulate an HLE-friendly hardware layout

This is to better represent the hardware layout, they are still aren't quite accurate, but this better and will help a bit when implementing the other archives like NAND-RO and NAND-RW

Fixed a few warnings and cleaned up the code

They will be stored in /extsavedata/SDMC and /extsavedata/NAND respectively.
Also redirect some APT_A functions to their APT_U equivalents.
Implemented the gamecoin.dat file in SharedExtSaveData in the PTM module.
Implemented formatting the savegame.
Retake a previous savegame if it exists instead of reporting them as not formatted every time a game is loaded.

It will be stored in the /syssavedata folder. This archive is user by various Services and possibly games via the FS:U service.

The savedata for each game is stored in /savedata/<ProgramID> for NCCH files. ELF files and 3DSX files use the folder 0 because they have no ID information

Got rid of the code duplication in File and Directory

Files that deal with the host machine's file system now live in DiskFile, similarly for directories and DiskDirectory and archives with DiskArchive.

FS_U: Use the correct error code when a file wasn't found

Uses QSettings on citra-qt, and inih on citra-cli.

Core: Fix the SDMC Directory implementation to make blargSnes work.

Also replaced C headers with the C++ equivalent ones