Integrations: Instance-level and project-level configuration
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As part of https://gitlab.com/groups/gitlab-org/-/epics/2137, we are moving *Service templates* to become instance-level service configuration.
We are simplifying the problem taking away the group-level configuration at the moment. This is how is going to look like:
```plantuml
#white:Instance;
split
#white:Project A;
detach
split again
#white:Project B;
detach
```
Main ideas that we have to explore, implement, deliver and communicate:
- Admin *Service Templates* will become instance-level service configuration.
- Project-level service configuration can override instance-level service configuration.
- Instance-level service configuration changes automatically propagate to the project-level service configuration.
### Todos
* [x] Create wireframes/mockups of entire workflow https://gitlab.com/gitlab-org/gitlab/-/issues/208008
* [x] Instance-level integration list page
* [x] Instance-level integration config page
* [x] Service template config page
* [x] ~~Write blog post that explains how Service Templates -> Integrations [TBD]~~
* [x] Add instance level integrations as separate feature
* [x] Engineering: Implement Instance-Level Integration Alongside Service Templates
* [x] Re-add “template” column, copy over “instance” values, and set to nil [https://gitlab.com/gitlab-org/gitlab/issues/204801]
* [x] Frontend implementation [https://gitlab.com/gitlab-org/gitlab/issues/196525] [https://gitlab.com/gitlab-org/gitlab/issues/208914]
* [x] Backend implementation [https://gitlab.com/gitlab-org/gitlab/issues/199388]
* [x] Final integration: Frontend, Backend and Docs [https://gitlab.com/gitlab-org/gitlab/-/issues/212290]
* [x] Consider setting a feature flag to work on frontend and backend independently
* [x] Add banner to service templates notifying user of new feature and future deprecation [https://gitlab.com/gitlab-org/gitlab/issues/204785]
* [x] ~~Link to a blog post explaining the change~~
* [x] Add banner notifying instance integration of existing service template that would override [https://gitlab.com/gitlab-org/gitlab/issues/204807]
* [x] Add feature displaying projects overriding settings to instance integrations [https://gitlab.com/gitlab-org/gitlab/-/issues/218252]
* [x] Add Telemetry for Enabled Instance-Level Integrations [https://gitlab.com/gitlab-org/gitlab/issues/204802]
* [x] Add feature to migrate an existing service template to an instance integration [https://gitlab.com/gitlab-org/gitlab/issues/204804]
- *NOTE: Customers have tooling that use the API and checks integration settings on a daily basis*
* [ ] API considerations
epic