Migrates Snowplow backend from EE to CE

What does this MR do?

As a continuation to https://gitlab.com/gitlab-org/telemetry/issues/58, we're migrating the Snowplow application settings out of EE and into CE. This MR focuses primarily on the backend code related to tracking and is intended to expose the relevant tracking interfaces to the CE project. It does not introduce any new event tracking.

CE MR can be found at https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/31199

We're intentionally not exposing any documentation on this yet, and will provide more clear documentation that reflects https://docs.gitlab.com/ee/development/fe_guide/event_tracking.html but for the backend when we start introducing more events to the tracking strategy.

Does this MR meet the acceptance criteria?

Conformity

• Changelog entry (already covered in https://gitlab.com/gitlab-org/gitlab-ee/merge_requests/14834)
• [ ] Documentation created/updated or follow-up review issue created
• Code review guidelines
• Merge request performance guidelines
• Style guides
• [ ] Database guides
• Separation of EE specific content

Risks

This does expose the settings, but doesn't introduce the tracking logic for any events. I'm not certain if we should add a comment to the admin interface or keep the interface hidden until there are more tracking events implemented within CE?

• Review and add/update tests for this feature/bug. Consider all test levels. See the Test Planning Process.
• [ ] Tested in all supported browsers

Security

If this MR contains changes to processing or storing of credentials or tokens, authorization and authentication methods and other items described in the security review guidelines:

• ~~[ ] Label as security and @ mention @gitlab-com/gl-security/appsec~~
• The MR includes necessary changes to maintain consistency between UI, API, email, or other methods
• [ ] Security reports checked/validated by a reviewer from the AppSec team