Implement checksums properly in dataplane

[shaneutt]

Problem Statement

We currently don't handle checksums properly or at all in several places. The purpose of this task is to get that sorted out.

Acceptance Criteria

• find all the places we are currently handling, or NOT handling L3 and L4 checksums and get them consistent
• use helpers like bpf_l3_cksum_replace to properly recalculate checksums

[astoycos]

Opening this up as a good issue for newcomers interested in getting involved in the ebpf dataplane bits :)

[LCaparelli]

Would like to work on this one o/

[astoycos]

@LCaparelli I would recommend joining the AYA discord If you're going to dive in here -> https://aya-rs.dev/community/

I already asked how to fix this bug here https://discord.com/channels/855676609003651072/1039654899408982077

[LCaparelli]

Yup, the nice folks over there already gave me a hand on the other issue I'm working on to improve the build process, thanks for the heads up @astoycos