feat(internal/config): Introduce internal config package

[mtoffl01]

…ct, ConfigSource object, and tests

What does this PR do?

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.
• New code is free of linting errors. You can check this by running ./scripts/lint.sh locally.
• 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: 2025-10-30 18:50:50

Comparing candidate commit 85ae251 in PR branch mtoff/config-revamp with baseline commit e1b2c3b in branch main.

Found 0 performance improvements and 0 performance regressions! Performance is the same for 24 metrics, 0 unstable metrics.

[datadog-official]

⚠️ Tests

⚠️ Warnings

🧪 1 Test failed

TestLogFormat from github.com/DataDog/dd-trace-go/v2/ddtrace/tracer (Datadog)

Failed

=== RUN   TestLogFormat
    log_test.go:193: 
        	Error Trace:	/home/runner/work/dd-trace-go/dd-trace-go/ddtrace/tracer/log_test.go:193
        	Error:      	"[]" should have 1 item(s), but has 0
        	Test:       	TestLogFormat
--- FAIL: TestLogFormat (0.01s)
panic: runtime error: index out of range [0] with length 0 [recovered]
	panic: runtime error: index out of range [0] with length 0
...

ℹ️ Info

❄️ No new flaky tests detected

_{This comment will be updated automatically if new data arrives.
🔗 Commit SHA: 85ae251 | Docs | Datadog PR Page | Was this helpful? Give us feedback!}