feat: added oci-s3 compatibility (#4374)

# What does this PR do?
The PR validates and allow access to OCI object-storage through the S3
compatibility API. Additional documentation for OCI is supplied, in
notebook form, as well.

## Test Plan
<!-- Describe the tests you ran to verify your changes with result
summaries. *Provide clear instructions so the plan can be easily
re-executed.* -->

---------

Co-authored-by: raghotham <rsm@meta.com>

src/llama_stack/providers/remote/files/s3/README.md

@@ -210,6 +210,35 @@ config:
   aws_secret_access_key: minioadmin
 ```
 
+### Using OCI Object Storage with S3 Compatibility
+[Official Object Storage Amazon S3 Compatibility API Documentation](https://docs.oracle.com/en-us/iaas/Content/Object/Tasks/s3compatibleapi.htm)
+
+OCI Object Storage can be utilized through the OCI S3 Compatibility API. Simply Update the `config.yaml` and set the env-vars as below.
+
+#### config.yaml
+```yaml
+provider_type: remote::s3
+config:
+  bucket_name: "${env.S3_BUCKET_NAME}"
+  region: "${env.AWS_REGION:=us-east-1}"
+  aws_access_key_id: "${env.AWS_ACCESS_KEY_ID:=}"
+  aws_secret_access_key: "${env.AWS_SECRET_ACCESS_KEY:=}"
+  endpoint_url: "${env.S3_ENDPOINT_URL:=}"
+  metadata_store:
+    table_name: files_metadata
+    backend: sql_default
+```
+#### .env
+```
+AWS_ACCESS_KEY_ID=OCI_ACCESS_KEY
+AWS_SECRET_ACCESS_KEY=OCI_SECRET_KEY
+S3_BUCKET_NAME=OCI_BUCKET_NAME
+S3_ENDPOINT_URL=https://<namespace>.compat.objectstorage.<region>.oci.customer-oci.com
+AWS_REQUEST_CHECKSUM_CALCULATION=when_required
+AWS_RESPONSE_CHECKSUM_VALIDATION=when_required
+```
+
+
 ## Monitoring and Logging
 
 The provider logs important operations and errors. For production deployments, consider: