feat(storage): add Huawei Cloud OBS object storage client implementation

[enbiyagoral]

What this PR does / why we need it:
Adds native support for Huawei Cloud Object Storage Service (OBS) as a chunk storage backend for Loki. This enables users in regions where Huawei Cloud is the primary cloud provider to use Loki with their existing infrastructure.

Which issue(s) this PR fixes:
N/A - New feature

Special notes for your reviewer:

• This implementation follows the same patterns as other cloud provider implementations (Alibaba OSS, AWS S3, Azure Blob)
• All ObjectClient interface methods are implemented with proper error handling
• Unit tests are included for configuration and error detection
• If you need test credentials to verify the implementation, I can provide temporary Huawei Cloud OBS credentials and a test bucket for integration testing. Please let me know if you'd like access.

Checklist

• Reviewed the CONTRIBUTING.md guide (required)
• Documentation added
• Tests updated
• Title matches the required conventional commits format, see here
  • Note that Promtail is considered to be feature complete, and future development for logs collection will be in Grafana Alloy. As such, feat PRs are unlikely to be accepted unless a case can be made for the feature actually being a bug fix to existing behavior.
• Changes that require user attention or interaction to upgrade are documented in docs/sources/setup/upgrade/_index.md
• If the change is deprecating or removing a configuration option, update the deprecated-config.yaml and deleted-config.yaml files respectively in the tools/deprecated-config-checker directory. Example PR

[CLAassistant]

All committers have signed the CLA.