[FEATURE] simplify inheriting opt values from config.yaml for svc pipeline cmd

[dennisseah]

closes microsoft/bedrock#1314

before this, we do not check if personal access token, org name and project name are provided or can be inherited from config.yaml.

added inherit properties to command decorator json file and use
populateInheritValueFromConfig and validateForRequiredValues functions to inherit values from config.xml and check that all mandatory options have values respectively. hence removing code of performing the above tasks in pipeline.ts file

[dennisseah]

pipeline: fabrikam-hld-to-fabrikam-manifests-408:
pipeline_status this iteration --> "completed"
Successful build for pipeline: fabrikam-hld-to-fabrikam-manifests-408!
info:    Generating config.yaml from yaml file input.
info:    config.yaml was generated and located at /Users/veseah/.spk/config.yaml.
info:    Successfully initialized the spk tool!
Start Time           Service      Deployment   Commit  Src to ACR Image Tag                                             Result ACR to HLD Env    Hld Commit Result HLD to Manifest Result
4/6/2020, 3:07:44 PM fabrikam2019 1e2e132b6505 7b27451 657        fabrikam2019-fabrikam.acme.frontend:master-20200406.1 ✓      657        MASTER bab4568    ✓      658             ✓     
1 deployment(s) were returned by spk deployment get
Verified that srcPipeline:657 acrPipelineId:657 hldPipelineId:658 pullrequest:"337" are all linked together correctly.
Successfully reached the end of spk deployment get tests.