reworked manifest handling

- manifest files wont be created unless symbols are resolved
- delay mt.exe presence check until we launch it
- create explicit case that writes manifests to disk
- moved manifest dependency collection step to happen after obj input
- removed /rad_delete_manifest

src/linker/lnk_error.h

@@ -28,6 +28,7 @@ typedef enum
   LNK_Error_UnsupportedMachine,
   LNK_Error_Mt,
   LNK_Error_UnableToSerializeMsf,
+  LNK_Error_LoadRes,
   LNK_Error_StopLast,
   
   LNK_Error_First,