feat: add system managed groups for all admins, viewers, and all org members

[golanglemonade]

Auto-creates three groups for new organizations (excluding personal orgs).

1. Admins - includes all users with the owner or admin role in the organization
2. Viewers - includes all users with the member role in the organization
3. All Members - includes all users in the organization

These groups can not be manually updated and the isManaged field is not exposed on update/create operations.

go run cmd/cli/main.go group get                                       
  ID                          NAME         DISPLAY NAME  DESCRIPTION                                         VISIBILITY  MANAGED  ORGANIZATION  MEMBERS  
  01JGJ3ZRFQVVFMC8S0TXFTDZGW  Admins       Admins        Openlane managed group containing all organization  PUBLIC      true     meowmeow      2        
                                                         admins with full access                                                                         
  01JGJ3ZRFQVVFMC8S0V18YW6V9  Viewers      Viewers       Openlane managed group containing all organization  PUBLIC      true     meowmeow      1        
                                                         members with only view access                                                                   
  01JGJ3ZRFQVVFMC8S0V5ZGQ6CH  All Members  All Members   Openlane managed group containing all members of    PUBLIC      true     meowmeow      3        
                                                         the organization   

Attempts to update group members of a managed group results in an error:

go run cmd/cli/main.go group-members create -u 01JGJ4056VVHQ7GHHAC0M0R9R5 -g 01JGJ5SDZVHHWHKAKZ4QX2X67X
Error: {"networkErrors":null,"graphqlErrors":[{"message":"managed groups cannot be modified","path":["createGroupMembership"]}]}

Resolves: #229

[sonarqubecloud]

Quality Gate failed

Failed conditions
6.3% Coverage on New Code (required ≥ 20%)

See analysis details on SonarQube Cloud