[Core feature] support pod plugin for ContainerTasks

[flixr]

Motivation: Why do you think this is important?

ContainerTasks currently don't support the pod plugin so we can't use it to control the pod and e.g. mount additional volumes or inject env vars and secrets.

Goal: What should the final outcome look like, ideally?

ContainerTask supports specifying pod spec.

Describe alternatives you've considered

Not using flyte...

Propose: Link/Inline OR Additional context

No response

Are you sure this issue hasn't been raised already?

• Yes

Have you read the Code of Conduct?

• Yes

[hamersaw]

To add a little more context here - this issue is very similar to the existing request to add Pod configuration to python tasks. However, this should apply specifically to the ContainerTask, so something like:

calculate_ellipse_area_shell = ContainerTask(
    name="ellipse-area-metadata-shell",
    ...
    pod=PodConfig(),
)

[flixr]

Actually I think this should be labeled as a bug not a feature...
Here is a simple repro:

Run this workflow and check the logs which should print the POD_SPEC_VAR env var:

from flytekit import workflow, ContainerTask
from flytekitplugins.pod import Pod
from kubernetes.client.models import V1Container, V1PodSpec, V1EnvVar

def gen_pod():
    pod_spec_var = V1EnvVar(name="POD_SPEC_VAR", value="yay")
    primary_container = V1Container(name="primary", env=[pod_spec_var])
    pod_spec = V1PodSpec(containers=[primary_container])
    return Pod(pod_spec=pod_spec, primary_container_name="primary")

print_env = ContainerTask(
    name="container_env_test",
    image="ubuntu:22.04",
    task_config=gen_pod(),
    command=["env"]
)

@workflow
def wf():
    print_env()

[hamersaw]

Closing as completed in this PR.