Support for custom endpoint configuration in snapshot repository setup

[nikhilsbhat]

This PR introduces support for specifying a custom endpoint in the S3-based snapshot repository configuration. It allows users to define a custom S3-compatible storage endpoint instead of relying solely on AWS defaults.

✅ Changes

• Added support for endpoint configuration in snapshot repository settings.
• Enables use of custom or on-prem S3-compatible storage services.

🔧 Use Case
Useful for setups involving:

• MinIO or other S3-compatible backends
• VPC endpoints

🔗 Related Issue
Potentially fixes #1096

[cla-checker-service]

💚 CLA has been signed

[tobio]

Thanks for adding this in! Code LGTM. Are you able to:

• Sign the CLA
• Run make docs-generate and commit the result
• Add an entry to CHANGELOG.md for this PR

[nikhilsbhat]

Thanks for adding this in! Code LGTM. Are you able to:

• Sign the CLA
• Run make docs-generate and commit the result
• Add an entry to CHANGELOG.md for this PR

@tobio, thanks for the review! I've completed all of them. Let me know if there's anything else needed from my side.

[tobio]

LGTM, thanks for taking the time here!