[Feature Request] Add Alibaba Cloud OSS support with Assume Role authentication for Polaris

Currently, Polaris lacks native support for Alibaba Cloud OSS (Object Storage Service) with Assume Role authentication. While Polaris has excellent AWS S3 support, there is no equivalent implementation for Alibaba Cloud OSS users.

**Key Problems:**

1. **Missing OSS Authentication**: Polaris doesn't support OSS-specific authentication mechanisms, particularly Assume Role authentication which is widely used in enterprise Alibaba Cloud environments.

2. **No OSS Credential Provider**: Unlike AWS S3 which has comprehensive credential provider chains, there's no equivalent for OSS STS (Security Token Service) and RAM (Resource Access Management) integration.

3. **Enterprise Adoption Barrier**: Many organizations using Alibaba Cloud cannot adopt Polaris due to lack of proper OSS authentication support, especially Assume Role which is required for security compliance.

4. **Inconsistent Cloud Support**: While Polaris supports AWS S3 comprehensively, Alibaba Cloud users (one of the largest cloud providers globally) lack equivalent functionality.

This creates a significant gap for Alibaba Cloud users who want to leverage Polaris for their data lakehouse architecture.

### Describe the solution you'd like

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### Describe alternatives you've considered

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### Additional context

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The issue names no files, tests, or entry points. Start by locating Polaris’s existing AWS S3 support and any related credential-provider tests, then define the OSS Assume Role integration; done means native Alibaba Cloud OSS support with STS/RAM authentication and coverage for the relevant flows.

Written by the indexing model from the issue text.