Automatic merge from submit-queue

Move predicates into library

This PR tries to implement #12744 

Any suggestions/ideas are welcome. @davidopp 

current state: integration test fails if including podCount check in Kubelet.
    
DONE:
    1. refactor all predicates: predicates return fitOrNot(bool) and error(Error) in which the latter is of type PredicateFailureError or InsufficientResourceError
    2. GeneralPredicates() is a predicate function, which includes serveral other predicate functions (PodFitsResource, PodFitsHost, PodFitsHostPort). It is registered as one of the predicates in DefaultAlgorithmProvider, and is also called in canAdmitPod() in Kubelet and should be called by other components (like rescheduler, etc if necessary. See discussion in issue #12744
TODO:
    1. determine which predicates should be included in GeneralPredicates()
    2. separate GeneralPredicates() into: a.) GeneralPredicatesEvictPod() and b.) GeneralPredicatesNotEvictPod()
    3. DaemonSet should use GeneralPredicates()