feat: LRU cache for flows in packetparser

[nddq]

Description

This PR optimizes the packetparser plugin by introducing an LRU cache to reduce memory and CPU usage under heavy traffic. Instead of generating a new Flow object for each packet event, the cache stores Flow objects based on source/destination IPs, ports, protocol, and direction. Packet events with matching values will reuse the existing Flow object, preventing excessive ToFlow invocations and potential OOM kills for the agent.

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Checklist

• I have read the contributing documentation.
• I signed and signed-off the commits (git commit -S -s ...). See this documentation on signing commits.
• I have correctly attributed the author(s) of the code.
• I have tested the changes locally.
• I have followed the project's style guidelines.
• I have updated the documentation, if necessary.
• I have added tests, if applicable.

Screenshots (if applicable) or Testing Completed

Over a similar period of time under the same workload, the total memory allocation for ToFlow without cache

vs with cache

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