Add offset_pagination resolver helper

What does this MR do?

This MR adds a new convenience method to BaseResolver which simplifies returning an offset-paginated connection.

This developer facing tooling change does not require a changelog.

Does this MR meet the acceptance criteria?

Conformity

• [-] Changelog entry
• Documentation (if required)
• Code review guidelines
• Merge request performance guidelines
• Style guides
• Database guides
• Separation of EE specific content

Availability and Testing

This should not change existing behavior, so no new tests are added.

• Review and add/update tests for this feature/bug. Consider all test levels. See the Test Planning Process.