Introduce AvailableServices singleton for accessing data

What does this MR do and why?

Introduce CloudConnector::AvailableServices singleton

For SelfManaged

• we will read CloudConnector::Access database record
• we will use CDOT issued token

Goal

Use CloudConnector::AvailableServices singleton as an interface to get information about CC service.

Note: We currently have CloudConnecor::AccessService with a similar purpose. The goal is to provide a more generic interface. In this iteration, the legacy CloudConnecor::AccessService is still used. In this iteration, the CloudConnecor::AvailableServices singleton is not yet used. I plan to remove CloudConnecor::AccessService in a separate merge request and replace the hardcoded checks/and usage.

  service = CloudConnector::AvailableServices.find_by_name(:duo_chat)

  service.free_acccess?      # checks if service is available for free (the cut_off_date is in the future) 
  service.allowed_for?(user) # checks if the user is assigned to one of the add-on seats that are bundled with the service.
  service.access_token       # Returns access token

In the next iteration (!148543 (closed)), the plan is to reduce the gap between SM and Gitlab.com by using CloudConnector::AvailableServices singleton for both Gitlab.com and Self-Managed instances.

MR acceptance checklist

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Before	After

How to set up and validate locally

Numbered steps to set up and validate the change are strongly suggested.

To simulate add-on purchases and seat assignments

add_on = GitlabSubscriptions::AddOn.find_or_create_by_name(:code_suggestions, nil)
add_on_purchase = ::GitlabSubscriptions::AddOnPurchases::CreateService.new(nil, add_on, {quantity: 10, expires_on: Time.current + 6.months, purchase_xid: 1})
seat_assigment = ::GitlabSubscriptions::UserAddOnAssignments::SelfManaged::CreateService.new(add_on_purchase: add_on_purchase, user: User.last).execute

To test Self Managed flow

To remove free access for duo_chat

Add cut_off_date: 2024-02-15 00:00:00 UTC in CloudConnector::Accesss data column:

   pry(main)> access_data = CloudConnector::Access.create(data: {"available_services"=>[{"name"=>"code_suggestions", "bundledWith"=>. 
      ["code_suggestions"], "minGitlabVersion"=>nil, 
      "serviceStartTime"=>"2024-02-15T00:00:00Z"}, {"name"=>"duo_chat", "serviceStartTime"=>"2024-02-15T00:00:00Z", "bundledWith"=>["code_suggestions"], "minGitlabVersion"=>"16.8", 
      "serviceStartTime"=>nil}]}

Test Steps

1. Create new CloudConnector::Access record

     pry(main)> access_data = CloudConnector::Access.create(data: {"available_services"=>[{"name"=>"code_suggestions", "bundledWith"=>["code_suggestions"], "minGitlabVersion"=>nil, 
     "serviceStartTime"=>"2024-02-15T00:00:00Z"}, {"name"=>"duo_chat", "bundledWith"=>["code_suggestions"], "minGitlabVersion"=>"16.8", 
     "serviceStartTime"=>nil}]}

2. Start rails console:

     bundle exec rails c

3. Clear the cache:

     CloudConnector::AvailableServices.clear_services_cache!

4. Use CloudConnector::AvailableServices.find_by_name to find the service

     pry(main)> service = CloudConnector::AvailableServices.find_by_name(:duo_chat)
     => #<CloudConnector::SelfManaged::AvailableServiceData:0x000000013d934d90 @add_on_names=["code_suggestions"], @allowed_scopes_during_free_access=[:duo_chat], @bundled_with={"code_suggestions"=>[:duo_chat]}, @cut_off_date=nil, @name=:duo_chat>
     
     pry(main)> service.free_access?
     => false
   
   
     pry(main)> service.access_token
     => "eyJ0eXAiOiJKV1QiLCJhbGciOiJSUzI1NiJ9.eyJqdGkiOiI1NGM3ZWIzOS1mODQ4LTQxOTEtOTI5Yy0xODBkNTJiMWYzYjAiLCJhdWQiOiJnaXRsYWItYWktZ2F0ZXdheSIsImlzcyI6Imh0dHA6Ly9sb2NhbGhvc3Q6NTAwMC8iLCJpYXQiOjE3MDc0OTUzOTQsIm5iZiI6MTcwNzQ5NTM4OSwiZXhwIjoxNzA3NzU0NTk0LCJnaXRsYWJfcmVhbG0iOiJzZWxmLW1hbmFnZWQiLCJzY29wZXMiOlsiY29kZV9zdWdnZXN0aW9ucyIsImR1b19jaGF0Il19.hHZEDBkQY9aSlP3aUVj6TAQP2XBPv-7QvggB6DiAHZhhdZtLVkdSY-dYLdZ8XLKi9ng5HiA-5q55Taw3ZjErK-xLkE1uzd4_AbLFRSdtRvv7iMioWG4kCsy67-MaSQ-um4av_KUkEQEZRlEWeEBx6GgPdIPGypp02dtbK1Gr7aTpjyx15_pTg_aflu8BJTjVQGAgi1_38uwzKRZlFsSxDTUKGoMhL3UZURQCc-Y1rRe1he-tKrd_-95ae6ozOKzQhN_51ZMEfxsbYxhurr2YGas0V_-zFrnulQhco0jGQeL3OZPPW6CLtw1rRc5pQ1WI47IStPkeqyz-u4pBoNN7WQ"
   
    pry(main)> service.allowed_for?(User.last)
    User Load (1.6ms)  SELECT "users".* FROM "users" ORDER BY "users"."id" DESC LIMIT 1 
    /*application:console,db_config_name:main,console_hostname:Nikolas-MacBook-Pro.local,console_username:nikola,line:(pry):9:in `__pry__'*/
    => true
   

Related to https://gitlab.com/gitlab-org/customers-gitlab-com/-/issues/8975