[FEATURE] Implement Disk-Based Buffering with Outbox Pattern Support for Elastic.Serilog.Sinks

I would like to request a feature enhancement for the `Elastic.Serilog.Sinks` NuGet package. The current implementation lacks disk-based buffering, which is crucial for ensuring log durability, especially in distributed applications.

**Proposed Feature:**

- Disk-Based Buffering: Implement disk-based buffering (as opposed to RAM) to enhance persistence and avoid potential data loss during high-throughput scenarios or application crashes.

- Outbox Pattern: Integrate the outbox pattern to ensure maximum durability when sending logs to Elasticsearch. This will prevent the need for additional tools like `Filebeat` for log durability, simplifying the logging pipeline.

**Importance:**

- Distributed Applications: Given the rise of distributed systems, it is essential to consider scenarios where multiple instances of an application might be logging concurrently. Ensuring that logs are reliably captured and forwarded to Elasticsearch is critical to maintaining observability in such environments.

By incorporating these features, the `Elastic.Serilog.Sinks` package can significantly improve its robustness and become a more reliable logging solution in distributed and high-throughput applications.

Thank you for considering this request!

No files, tests, or entry points are named. Start by reviewing the current Elastic.Serilog.Sinks buffering and Elasticsearch delivery implementation, then clarify the disk durability and outbox requirements for concurrent distributed instances. Done means the package supports durable disk-based buffering and outbox-style forwarding without requiring Filebeat.

Written by the indexing model from the issue text.