[PLUGIN-1778] Add schema management to remote task execution flow in Wrangler service

[vanathi-g]

Changes

• Add new inputSchema field to RemoteDirectiveRequest
• Set the inputSchema obtained from request in TransientStore created in RemoteExecutionTask
• Add a new RemoteDirectiveResponse class that wraps the output rows and output schema together for returning from RemoteExecutionTask

[tivv]

This looks like a specific case handling. Any other TransientStore usage won't work. Should we just serialize and send the whole store over the wire both ways?

[vanathi-g]

Thanks for pointing that out @tivv. I did initially implement that approach with the type handler for serializing the transient store: eb981ab

But then later I thought that sending the entire transient store might add unnecessary overhead and if there are serialization/deserialization issues with some other variable in the store, schema handling would break.

We can add it back in as a follow up item with more rigorous testing maybe? Right now this issue is a release blocker so I tried to fix it with minimal changes

[vanathi-g]

@samdgupi seeing that you have added a kryo serializer for rows in a previous PR under a feature flag, you have to add support for schema as well now

[tivv]

Please add a comment to TransientStoreKeys to update this code on any additonal values

[samdgupi]

@samdgupi seeing that you have added a kryo serializer for rows in a previous PR under a feature flag, you have to add support for schema as well now

@vanathi-g Updated KryoSeializer to support RemoteDirectiveResponse. Please check the PR and give LGTM

[vanathi-g]

LGTM, looks like there are build issues due to checkstyle