Remove msgpack from python-sdk and support application/json response from rust server #1025 and #1030

[Default2882]

Context

Completely removes dependency on msgpack in python-sdk, and now indexify supports both json and bytes encoding for input data. This change is for #1025 and #1030.

Testing

Added new graph behaviour test for graph with json as well as cloudpickle encoding.

Manual Testing -

1. Invoking graph with json data where the start node has json encoding -

curl -H 'Content-Type: application/json' -d '{"x":"a","y":"10"}' -X POST http://localhost:8900/namespaces/default/compute_graphs/test_different_encoders/invoke_object

data: {"id":"dce70b20f0ab1a65"}

2. Downloading output from a function with json encoding -

curl http://localhost:8900/namespaces/default/compute_graphs/test_different_encoders/invocations/db1919fac416a39a/fn/simple_function_multiple_inputs_json/output/70cd3c246dd5f2f9 -s | jq

"\"abbbbbbbbbb\""

3. Downloading invoked payload of graph invocation where the start node has json encoding -

curl http://localhost:8900/namespaces/default/compute_graphs/test_different_encoders/invocations/db1919fac416a39a/payload -s | jq

{
  "x": "a",
  "y": 10
}

Contribution Checklist

• [Done] If the python-sdk was changed, please run make fmt in python-sdk/.
• [Done] If the server was changed, please run make fmt in server/.
• [Done] Make sure all PR Checks are passing.

[diptanu]

@Default2882 This looks fine to me. Let's merge this once we have the other pieces for doing JSON end to end.