[New Scheduler] Add container message consumer

[upgle]

Description

The container message consumer subscribes to Kafka's containerCreation topic and handles container creation/deletion requests.

The FPCInvokerReactive, which will be newly added, uses this consumer.

Related issue and scope

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

My changes affect the following components

• New scheduler

Types of changes

• 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.

[codecov-commenter]

Codecov Report

Merging #5111 (4ee105b) into master (f1829e1) will decrease coverage by 6.17%.
The diff coverage is 59.42%.

@@            Coverage Diff             @@
##           master    #5111      +/-   ##
==========================================
- Coverage   81.86%   75.69%   -6.18%     
==========================================
  Files         225      226       +1     
  Lines       11423    11470      +47     
  Branches      501      491      -10     
==========================================
- Hits         9352     8682     -670     
- Misses       2071     2788     +717     

Impacted Files	Coverage Δ
.../org/apache/openwhisk/core/connector/Message.scala	75.12% <6.25%> (+2.07%)	⬆️
.../scala/org/apache/openwhisk/core/entity/Size.scala	79.10% <50.00%> (ø)
...nwhisk/core/invoker/ContainerMessageConsumer.scala	78.72% <78.72%> (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%)	⬇️
... and 22 more

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[ningyougang]

@upgle , i am sorry, due to test case error and sub prs depend on this pr, i submited a commit for this pr to solve the test case error.