tracer: report config-change telemetry in dynamic config

[ahmed-mez]

What does this PR do?

AIT-8580

Report configuration changes applied via dynamic configuration. This required some refactoring of the current dynamicConfig implementation with an intent to keep it as generic as possible.
More logic was added to avoid unnecessary reconfigurations and unnecessary (or inaccurate) config change telemetry events in case of an attempt to reconfigure the same value.

This what an example payload looks like

{"api_version":"v2","request_type":"app-client-configuration-change","tracer_time":1699955789,"runtime_id":"9d6b96e5-6d6f-4d33-92e8-756b31d69776","seq_id":3,"debug":false,"payload":{"configuration":[{"name":"trace_sample_rate","value":0.7,"origin":"remote_config","error":{"code":0,"message":""},"is_overridden":false}]},"application":{"service_name":"my.go.service","env":"staging","service_version":"v1","tracer_version":"v1.57.0-dev","language_name":"go","language_version":"go1.20.5","runtime_name":"","runtime_version":""},"host":{"hostname":"REDACTED","os":"darwin","os_version":"13.6","architecture":"arm64","kernel_name":"","kernel_release":"","kernel_version":""}}

Motivation

Bette UX for dynamic config: the reported active configuration will be shown on the UI.

Reviewer's Checklist

• Changed code has unit tests for its functionality at or near 100% coverage.
• 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.

For Datadog employees:

• If this PR touches code that handles credentials of any kind, such as Datadog API keys, I've requested a review from @DataDog/security-design-and-guidance.
• This PR doesn't touch any of that.

Unsure? Have a question? Request a review!

[pr-commenter]

Benchmarks

Benchmark execution time: 2023-11-16 08:38:33

Comparing candidate commit 759226d in PR branch ahmed/dynamic-config-part4 with baseline commit bd47d89 in branch main.

Found 0 performance improvements and 0 performance regressions! Performance is the same for 40 metrics, 1 unstable metrics.