introduce "wait then" behaviour between rules to avoid race conditions

Description -

At the moment rules are triggered in a sequence determined by the rule order number.  However, each rule executes asynchronously meaning that rules with a higher priority may finish after rules with a lower priority.   This can cause issues where there is a dependency between rules. 

Why is this feature important to you -

We are experiencing issues where there are dependencies between rules.  They are hard to spot because the are intermittent and are difficult to resolve due the the asynchronous execution. 

How would you like the feature to work -

I would like to be able to force rules set to different order numbers to wait for other rules. This would be similar to the "wait then" behaviour of actions within a rule.