Add fw dumping

- also fatfs is stupid
- also close files properly on a failed copy
- also check for errors during folder readouts
- also make sure holding vol- doesn't dump the keys anyway

source/fs/fsutils.h

@@ -5,4 +5,5 @@
 u64 GetFileSize(char *path);
 char *EscapeFolder(const char *current);
 char *CombinePaths(const char *current, const char *add);
-char *GetFileAttribs(FSEntry_t entry);
+char *GetFileAttribs(FSEntry_t entry);
+bool FileExists(char* path);