Function compare_thread_subscription_bump_stamps

pub fn compare_thread_subscription_bump_stamps(
    previous: Option<u64>,
    new: &mut Option<u64>,
) -> bool

Compare two thread subscription changes bump stamps, given a fixed room and thread root event id pair.

May update the newer one to keep the previous one if needed, under some conditions.

Returns true if the new subscription should be stored, or false if the new subscription should be ignored.