[FEATURE REQUEST] On-Premise S3 & Remote Signing

**Is your feature request related to a problem? Please describe.**
Currently Polaris only works for AWS S3. It would be great to get support for on-prem deployments as well!

**Describe the solution you'd like**
Add an additional storage profile similar to the [AWS one](https://github.com/polaris-catalog/polaris/blob/bb544239f0ca3bcd076cf2e93116b2747e289e10/spec/polaris-management-service.yml#L880) which allows custom Endpoint configuration. Test with MinIO or Ceph. Grant access via remote signing.

**Describe alternatives you've considered**
I don't think there is any?

**Additional context**
Remote signing spec: https://github.com/apache/iceberg/blob/main/aws/src/main/resources/s3-signer-open-api.yaml