add pool split-brain protection

[KaymeKaydex]

now the pool will not react in any way to the fact that 2 masters have appeared in the single master topology

I propose to introduce a double master type of behavior and return errors by default instead of executing a request to the pool

[oleg-jukovec]

How would you propose to implement this?

[KaymeKaydex]

Now I assume that the best solution would be some processing on the pool balancer interface. Get the total number of masters from them and make policies that will decide what to do in this case

however, I assume that this is blocked by the solution with balancers #400 . I tried to correctly prepare this interface in one go, but this clearly requires more effort

[KaymeKaydex]

I believe this policy will not allow you to completely protect against split brain, but it will allow you to quickly stop it if this was not intended