MinidumpWriterConfig.set_crash_context() can set a context with a different pid/tid than those in the configuration itself

Just bumped into this while reviewing Firefox bug 1980648. We're storing the process PID and blamed thread TID in the MinidumpWriterConfig object but the user can set different ones in MinidumpWriterConfig.set_crash_context(). It's not a big deal because we won't use these values when writing the minidump IIRC, but it feels a bit quirky.