feat: add method for pipeline validation to PipelineResource

[mathislucka]

We want to add a validate method to the PipelineResource. This method will call the validate endpoint and validate a pipeline's yaml config.

The request to the endpoint looks like this:

curl --request POST \
     --url https://api.cloud.deepset.ai/api/v1/workspaces/test_workspace/pipeline_validations \
     --header 'content-type: application/json' \
     --data '
{
  "deepset_cloud_version": "v2",
  "query_yaml": "This is where the yaml config goes."
}
'

To implement the feature, you need to make the following changes:

• remove .raise_for_status from AsyncTransportProtocol
• extend TransportResponse with a success (true/false property)
• set success to false if the status code is greater or equal to 400
• adapt any tests if needed

Now the actual implementation:

• add a validate method in PipelineResource

• the method accepts a yaml_config

• it returns a PipelineValidationResult (create the model)

• the API will return a 422 if the yaml_config is not valid yaml

• the API will return a 400 if there are errors in the config

• for 400 we will have an errors key with a list of code, message objects

• return the errors in the PipelineValidationResult

Add unit and integration tests following the conventions used in the existing tests.