[docs]: Add documentation and examples for FileSystem serdes

[dhegberg]

URL/Location

No response

Describe What's Incorrect or Lacking

Add documentation on using FileSystem serdes over the default serdes implementation.

Include details on EFS/S3 Files a a per-requisite (vs temporary local filesystem).
Include details on check-pointing tradeoffs when offloading to filesystem.
Include details on PII masking options.

JS release: https://github.com/aws/aws-durable-execution-sdk-js/releases/tag/sdk-2.0.0
Java parity: aws/aws-durable-execution-sdk-java#463
Python parity: aws/aws-durable-execution-sdk-python#479

Suggested Improvement

No response

Additional Context

No response