[AutoRest.Ruby] Inheritance usage of "Resource" is broken

[vishrutshah]

MsRestAzure does not have a class ProxyOnlyResource . Inheritance logic is buggy

Example: https://github.com/Azure/azure-sdk-for-ruby/blob/master/management/azure_mgmt_web/lib/generated/azure_mgmt_web/models/backup_item.rb#L11

AutoRest Code: https://github.com/vishrutshah/autorest.ruby/blob/master/src/azure/Model/CompositeTypeRba.cs#L51

Last changes to that model: https://github.com/Azure/autorest/pull/1769/files#diff-817aab60d4b1d87bb4f496c78f25e473R76

Some of other related problems are the swagger has marked the model wrong as x-ms-azure-resource. model ResourceUpdate is not a valid x-ms-azure-resource.

[vishrutshah]

Re-opening this as an issue did not get resolved correctly. This caused SubResource to not generate for azure_mgmt_datalake SDK for release of ARM 0.13.0.

Reverting this Azure/autorest.ruby#12