Explicitly call set_current_organization when a Grape controller needs it

What does this MR do and why?

Setting Current Organization is dependent on Current User. But the current_user method is not returning nil but rendering a Unauthorized HTTP response. So it can't be used in all API calls: for example some API endpoints support other tokens apart from Personal Access Token. Calling current_user while an API has a different authentication method will lead to an HTTP 401 Unauthorized status code.

I tried several options, see a list in the previous MR.

But in the end, I settled for a more explicit approach: Explicitly call set_current_organization if a Grape API controller needs it. All the API controllers that require Current.organization do now have the call to set_current_organization helper method.

There is a risk that developer will forget setting the current organization. To prevent that, an Error will be raised (not in production) with a descriptive error message. This error is disabled for Rails production environment.

[1] pry(main)> pp ::Current.organization
Current::OrganizationNotAssignedError: Assign an organization to Current.organization before calling it.
[2] pry(main)> ::Current.organization = Organizations::Organization.first
=> #<Organizations::Organization:0x0000000150f9f758 id: 1, created_at: Thu, 05 Sep 2024 06:42:35.939165000 UTC +00:00, updated_at: Thu, 05 Sep 2024 06:42:35.939165000 UTC +00:00, name: "Default", path: "default", visibility_level: 20>
[3] pry(main)> pp ::Current.organization
=> #<Organizations::Organization:0x0000000150f9f758 id: 1, created_at: Thu, 05 Sep 2024 06:42:35.939165000 UTC +00:00, updated_at: Thu, 05 Sep 2024 06:42:35.939165000 UTC +00:00, name: "Default", path: "default", visibility_level: 20>

Setting Current.organization=nil is also supported: it still counts as a assigment.

I had to add an exception for Gitlab::CurrentSetting: If Current.organization is not set, it will not read from OrganizationSetting

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Related to #482503 (closed)