Missing RenewSecret interface for Oauth Application
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### Problem
I would like to be able to rotate the GitLab Oauth Application secret using the SDK. This is normally done using the `POST /applications/:id/renew-secret` endpoint, which does not have an interface in the GitLab client-go.
Here is a link to the documentation of this particular endpoint: https://docs.gitlab.com/api/applications/#renew-an-application-secret
### Solution
Could this endpoint be added to the Application Service methodset ? We could imagine a `RenewSecret` method on the `ApplicationsServiceInterface`
## Implementation Guide
- Follow the `CONTRIBUTING.md` guide for setting up your local development environment.
- Clone the community fork of this project.
- In `applications.go`, add a new interface entry and function for the `RenewApplicationSecret` endpoint described in https://docs.gitlab.com/api/applications/#renew-an-application-secret
- In `applications_test.go`, add a new test for the new function.
issue