Support overriding task pod_template via with_overrides

[arbaobao]

Tracking issue

Related to https://github.com/flyteorg/flyte/issues/5683

Why are the changes needed?

If we can support pod_template in with_overrides, this would reduce a lot of toil since we can supply pod templates in a central location and override downstream tasks, similar to how we can do so for resources.

What changes were proposed in this pull request?

We can use with_override() to override podtemplate, just like resources.

How was this patch tested?

Excute a workflow and using with_override(pod_template=PodTemplate(xxx)) to override the default podtemplate

Setup process

Screenshots

Check all the applicable boxes

• [ ] I updated the documentation accordingly.
• [ ] All new and existing tests passed.
• [X] All commits are signed-off.

Related PRs

Docs link