Automatic merge from submit-queue (batch tested with PRs 40873, 40948, 39580, 41065, 40815)

[CRI] Enable Hostport Feature for Dockershim

Commits:
1. Refactor common hostport util logics and add more tests

2. Add HostportManager which can ADD/DEL hostports instead of a complete sync.

3. Add Interface for retreiving portMappings information of a pod in Network Host interface. 
Implement GetPodPortMappings interface in dockerService. 

4. Teach kubenet to use HostportManager