CFG: Implemented the GetConfigInfoBlk2 function.

Added a "config" file to the CFG process service (CFG:U), and added a few default blocks to it.

Implemented GetSystemModel and GetModelNintendo2DS
CFG:U: Add some data to the 0x00050005 config block.

Seems to allow some games to boot further, thanks @Normmatt for sharing this information
CFG: Refactored how the config file works.

It is now kept in memory as per 3dbrew, all updates happen on memory, then they can be saved using UpdateConfigNANDSavegame.
CFGU: Added block 0x000A0002 to the default savegame file

That's the language id block, we're using LANGUAGE_EN for now. This block allows some games to boot further
CFG: Load the Config savedata file if it already exists.
CFGU: Use an absolute offset in the config savefile blocks
CFG: Implemented block 0x00070001 in the config savefile
CFG:U: Implemented some more blocks
CFG_U: Use Common::make_unique instead of the std version
Style: Addressed some comments
CFGU: Addressed some comments.
CFGU: Addressed some issues.
CFGU: Some changes
CFG: Create a new subfolder cfg inside service to handle cfg

Moved most of the shared CFG code there, implemented a few CFG:I functions
CFG: Corrected the licenses in cfg_i.cpp and cfg_u.cpp
CFG: Changed the CreateConfigInfoBlk search loop
CFG: Some indentation
CFGU: Indentation
CFG: More style changes
CFG: Fixed some warnings and errors in Clang