pd-server v1.1.0-beta

• Add the Drop Region debug interface
• Support setting priority of the PD leader
• Support configuring stores with a specific label not to schedule Raft leaders
• Add the interfaces to enumerate the health status of each PD
• Add more metrics
• Keep the PD leader and the etcd leader together as much as possible in the same node
• Improve the priority and speed of restoring data when TiKV goes down
• Enhance the validity check of the data-dir configuration item
• Optimize the performance of Region heartbeat
• Fix the issue that hot spot scheduling violates label constraint
• Fix other stability issues