example/test implementation of ip4_output hooks

[tp-qomodo]

Description

Added ip4_output() and ip6_output() hooks which can be used by defining LWIP_HOOK_IP4_OUTPUT or LWIP_HOOK_IP6_OUTPUT inside ESP_IDF_LWIP_HOOK_FILENAME.

Related

I created an issue here: #75

Testing

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Checklist

Before submitting a Pull Request, please ensure the following:

• 🚨 This PR does not introduce breaking changes.
• All CI checks (GH Actions) pass.
• Documentation is updated as needed.
• Tests are updated or added as necessary.
• Code is well-commented, especially in complex areas.
• Git history is clean — commits are squashed to the minimum necessary.