feat(tracing): add anthropic streaming support

[wconti27]

Adds streaming support for Anthropic Integration and LLMObservability Integration

Checklist

• Change(s) are motivated and described in the PR description
• Testing strategy is described if automated tests are not included in the PR
• Risks are described (performance impact, potential for breakage, maintainability)
• Change is maintainable (easy to change, telemetry, documentation)
• Library release note guidelines are followed or label changelog/no-changelog is set
• Documentation is included (in-code, generated user docs, public corp docs)
• Backport labels are set (if applicable)
• If this PR changes the public interface, I've notified @DataDog/apm-tees.

Reviewer Checklist

• Title is accurate
• All changes are related to the pull request's stated goal
• Description motivates each change
• Avoids breaking API changes
• Testing strategy adequately addresses listed risks
• Change is maintainable (easy to change, telemetry, documentation)
• Release note makes sense to a user of the library
• Author has acknowledged and discussed the performance implications of this PR as reported in the benchmarks PR comment
• Backport labels are set in a manner that is consistent with the release branch maintenance policy

[datadog-dd-trace-py-rkomorn]

Datadog Report

Branch report: conti/add-anthropic-streaming-support
Commit report: cd3b1f1
Test service: dd-trace-py

✅ 0 Failed, 125 Passed, 85 Skipped, 1m 48.27s Total Time

[pr-commenter]

Benchmarks

Benchmark execution time: 2024-06-11 18:25:11

Comparing candidate commit 717bd6f in PR branch conti/add-anthropic-streaming-support with baseline commit 2e237a7 in branch main.

Found 0 performance improvements and 0 performance regressions! Performance is the same for 221 metrics, 9 unstable metrics.

[brettlangdon]

minor questions and nits

[brettlangdon]

minor suggestion about release note, otherwise lgtm