Implement BlReadFile() routine

xtldr2/includes/bootman.h

@@ -57,6 +57,13 @@ BlOpenVolume(IN PEFI_DEVICE_PATH_PROTOCOL DevicePath,
              OUT PEFI_HANDLE DiskHandle,
              OUT PEFI_FILE_HANDLE *FsHandle);
 
+XTCDECL
+EFI_STATUS
+BlReadFile(IN PEFI_FILE_HANDLE DirHandle,
+           IN CONST PWCHAR FileName,
+           OUT PVOID *FileData,
+           OUT PSIZE_T FileSize);
+
 XTCDECL
 VOID
 BlConsoleClearScreen();