App Manager

1. Add the AM module to move the engine management function previously done by Entrance to the AM module.
2. AM needs to support operating Engine, including: adding, multiplexing, recycling, preheating, switching and other functions.
3. AM needs to manage EM services, complete EM registration and forward the resource registration to RM.
4. AM needs to be connected to the Label module, including the addition and deletion of EM/Engine, the label manager needs to be notified to update the label.
5. AM also needs to dock the label module for label analysis, and need to obtain a list of serverInstances with a series of scores through a series of labels (How to distinguish between EM and Engine? the labels are completely different).
6. Need to provide external basic interface: including the addition, deletion and modification of engine and engine manager, metric query, etc.

Engine manager: Engine manager is responsible for managing the basic information and metadata information of all engines.