feat(inputs.statsd): Add support for Datadog service checks

[skartikey]

Summary

Add parsing support for Datadog service check messages (_sc format) when datadog_extensions is enabled. Service checks allow monitoring the status of external services and are commonly used by Datadog agents.

Service check format: _sc|<name>|<status>|d:<timestamp>|h:<hostname>|#<tags>|m:<message>

The parsed service checks produce metrics with measurement name "statsd_service_check" containing status code, status text, and optional message fields.

Checklist

• No AI generated code was used in this PR
• AI generated code used in this PR follows the InfluxData Policy on AI-Generated Code Contributions

Related issues

resolves #17480

[telegraf-tiger]

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