Baggage API v2

[rachelyangdog]

What does this PR do?

porting baggage api to v2

Motivation

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.
• For internal contributors, a matching PR should be created to the v2-dev branch and reviewed by @DataDog/apm-go.

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[pr-commenter]

Benchmarks

Benchmark execution time: 2025-01-21 19:29:04

Comparing candidate commit e86d745 in PR branch rachel.yang/baggage-api-v2 with baseline commit 519c69e in branch v2-dev.

Found 0 performance improvements and 0 performance regressions! Performance is the same for 51 metrics, 2 unstable metrics.