Migrate from USB/SD being hardcoded

[spotlightishere]

Many, many paths currently hardcode checks to usb:/ or sd:/, which is not preferable.

As it stands, we now have several functions to allow agnostic access of a volume hosted on a SD card or USB drive, depending on the user's preference:

OSCHomebrewBrowser/source/files.h

Lines 9 to 12 in 3f47f8e

	char *app_path(char *app_name, char *app_file);
	FILE *hbb_fopen(char *filename, const char *mode);
	char *device_name();
	char *temp_path();

We should migrate to removing these.