[New Scheduler] Implement FCPSchedulerServer

[ningyougang]

Description

This is the document for new Scheduler: https://cwiki.apache.org/confluence/display/OPENWHISK/New+architecture+proposal

Regarding FPCSchedulerServer, it provides some APIs to access the concrete info for scheduler node. including

• /state

curl -u xxx:'xxx' http://xxx.xxx.xxx.xxx:13001/state
{"0":"104","creationCount":"0"}    # it means  current scheduler node: `scheduler0` includes `104`  total queue,  has no creating queues 

• /queue/total

curl -u xxx:'xxx' http://xxx.xxx.xxx.xxx:13001/queue/total
104 # it means includes 104 total queues

• /queue/status

curl -u xxx:'xxx' http://xxx.xxx.xxx.xxx:13001/queue/status
[{
		"data": "RunningData(Actor[akka://scheduler-actor-system/user/$Qd#905522799],Actor[akka://scheduler-actor-system/user/$Pd#-785916053])",
		"fqn": "xxx@0.0.19",
		"invocationNamespace": "xxx",
		"status": "Running",
		"waitingActivation": 0
	}, {
		"data": "RunningData(Actor[akka://scheduler-actor-system/user/$Y#-32044316],Actor[akka://scheduler-actor-system/user/$X#-359037829])",
		"fqn": "xxx@0.0.4",
		"invocationNamespace": "xxx",
		"status": "Running",
		"waitingActivation": 0
	}
 ...
 ]

• disable
  When want to gracefully shutdown the scheduler, can invoke /disable

curl -u xxx:'xxx' -X POST http://xxx.xxx.xxx.xxx:13001/disable

Related issue and scope

• I opened an issue to propose and discuss this change (#????)

My changes affect the following components

• API
• Controller
• Message Bus (e.g., Kafka)
• Loadbalancer
• Invoker
• Intrinsic actions (e.g., sequences, conductors)
• Data stores (e.g., CouchDB)
• Tests
• Deployment
• CLI
• General tooling
• Documentation

Types of changes

• Bug fix (generally a non-breaking change which closes an issue).
• Enhancement or new feature (adds new functionality).
• Breaking change (a bug fix or enhancement which changes existing behavior).

Checklist:

• I signed an Apache CLA.
• I reviewed the style guides and followed the recommendations (Travis CI will check :).
• I added tests to cover my changes.
• My changes require further changes to the documentation.
• I updated the documentation where necessary.

[bdoyle0182]

let's put queue in a constant as it will likely be reused as new api's are added

[ningyougang]

Updated accordingly, thanks for your review!

[codecov-io]

Codecov Report

Merging #5030 (a8a1f83) into master (faae555) will decrease coverage by 6.34%.
The diff coverage is 76.19%.

@@            Coverage Diff             @@
##           master    #5030      +/-   ##
==========================================
- Coverage   82.10%   75.75%   -6.35%     
==========================================
  Files         200      207       +7     
  Lines        9760    10034     +274     
  Branches      447      444       -3     
==========================================
- Hits         8013     7601     -412     
- Misses       1747     2433     +686     

Impacted Files	Coverage Δ
...rg/apache/openwhisk/core/scheduler/Scheduler.scala	0.00% <0.00%> (ø)
.../openwhisk/core/scheduler/FPCSchedulerServer.scala	95.83% <94.11%> (ø)
...core/database/cosmosdb/RxObservableImplicits.scala	0.00% <0.00%> (-100.00%)	⬇️
...ore/database/cosmosdb/cache/CacheInvalidator.scala	0.00% <0.00%> (-100.00%)	⬇️
...e/database/cosmosdb/cache/ChangeFeedConsumer.scala	0.00% <0.00%> (-100.00%)	⬇️
...core/database/cosmosdb/CosmosDBArtifactStore.scala	0.00% <0.00%> (-95.85%)	⬇️
...sk/core/database/cosmosdb/CosmosDBViewMapper.scala	0.00% <0.00%> (-93.90%)	⬇️
...tabase/cosmosdb/cache/CacheInvalidatorConfig.scala	0.00% <0.00%> (-92.31%)	⬇️
...enwhisk/connector/kafka/KamonMetricsReporter.scala	0.00% <0.00%> (-83.34%)	⬇️
...e/database/cosmosdb/cache/KafkaEventProducer.scala	0.00% <0.00%> (-78.58%)	⬇️
... and 26 more

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[bdoyle0182]

LGTM

[ningyougang]

Have any comment?

[style95]

I think @bdoyle0182 already approved this PR and it has been so long so we can merge this if it passes all CI tests.