internal/osinfo: setup for kernel info

[eliottness]

What does this PR do?

This PR refactors the internal/osinfo to include kernel data and better OS info:

• try to open /etc/os-release on all UNIX systems
• Call to unix.Uname to access kernel Name, Release and Version
• Map this data to telemetry as described as mandatory in the telemetry spec
• Move all this to init functions because all of this is static data

Motivation

Fix reporting from telemetry and prepare for the new telemetry client revamp incoming.

Reviewer's Checklist

• Changed code has unit tests for its functionality at or near 100% coverage.
• System-Tests covering this feature have been added and enabled with the va.b.c-dev version tag.
• There is a benchmark for any new code, or changes to existing code.
• If this interacts with the agent in a new way, a system test has been added.
• Add an appropriate team label so this PR gets put in the right place for the release notes.
• Non-trivial go.mod changes, e.g. adding new modules, are reviewed by @DataDog/dd-trace-go-guild.

Unsure? Have a question? Request a review!

[pr-commenter]

Benchmarks

Benchmark execution time: 2024-10-24 08:46:10

Comparing candidate commit 4c13d60 in PR branch eliott.bouhana/better-osinfo with baseline commit 2edf445 in branch main.

Found 1 performance improvements and 0 performance regressions! Performance is the same for 58 metrics, 0 unstable metrics.

scenario:BenchmarkInjectW3C-24

• 🟩 execution_time [-174.820ns; -130.180ns] or [-4.037%; -3.007%]

[eliottness]

I have to add the go:build line there because of golang/go#20322 so I decided to add go:build to all the files that need it in this package