Support retrieval of YANG module sources for CM handle on the NCMP interface

CPS-Core (and NCMP)  has moduelService method to retrieve module-references (name and revision) for a given Anchor

See org.onap.cps.api.CpsModuleService#getSchemaSet

Issue: naming conflict possible "SchemaSet" already used to represent collection of references (possibly refactor to include flag to indicate yang-resources should be included)

NCMP need to be extended? so the response will include the actual 'yang-resources' 

Current Endpoint in NCMP:

/v1/ch/{cm-handle}/modules:

Possible 

1. /v1/ch/{cm-handle}/modules/yangResources
2. /v1/ch/{cm-handle}/yangResources
3. /v1/ch/{cm-handle}/modules&includeYangResources=true
4. Other ?

so effectively returns the whole SchemaSet

Agreed:

1. Rest endpoint
   1. /v1/ch/{cm-handle}/modules/definitions/
2. Response format
   1. Returns list of array (modules,revision, yangResource content)
   2. JSON
   3. to keep the ouput format of yang resource content having \n for newline based on swagger

A/C

1. Define & document sizes of SchemaSets ie. number of modules and average module size (for one SchemaSet)
2. Agree with team and stakeholders the exact rest endpoint and response format (consider plain text, objects, zipfile etc.)
3. Demo end-2-end

Out-of-Scope

1. No similar endpoint on CPS-Core just a Java-API method
2. CSIT test not need as the functionality is in the same process