[EXPERIMENTAL] Utf8 file path supported for windows platform

[C-ColinTH]

Feature:

• Now even if the game path contains non ASCII characters, it should be able to be recognized normally.
• Even if the file name of game PK3 package and other data files contains non ASCII characters, they should still be able to load normally.

Note: Testing well on my two win10 system computers, but more samples may be needed for this.

Build: Using UTF8 flag

for example: mingw32-make ARCH=x86_64 UTF8=1

[wolfetplayer]

Should be pretty useful for game path. Does it cover .cfg path in My Documents? Because this seems to be the most problematic issue in this regard.

[C-ColinTH]

Should be pretty useful for game path. Does it cover .cfg path in My Documents? Because this seems to be the most problematic issue in this regard.

I created non-ASCII name window user and test on two computers, they seem work well for Documents directory.

System: win10 22H2 19045.5965 win10 22H2 19045.6093

However, for other versions of the Windows system, I cannot guarantee too much as more devices may need be test.