[WIP - Don't review]Patch REST get_aggregated_tensor api for batched changes

[ishaileshpant]

Summary

For the changes in get_aggregated_tensors api as per #1575 PR we need to adjust the REST api spec and the rest client for the changes

Type of Change (Mandatory)

Patch REST get_aggregated_tensor api for batched changes as per https://github.com/securefederatedai/openfl/pull/1575

• rename the function to get_aggregated_tensors
• adjust both grpc and rest client for name and signature change in api
• for the protobuf changes of TensorSpeca and Batched response adjust both client and server in line with grpc
• fix the test cases

Description (Mandatory)

Current REST api implementation and the test cases needs to be adjusted for the api changes as per #1575