[Frontend] Refactor group projects dropdown

Why are we doing this work

1. ee/security_orchestration/components/group_projects_dropdown.vue now only supports loading of projects
2. Goal of this issue is to refactor the component so it can load groups/subgroups as well

Relevant links

1. Example design

Non-functional requirements

• Documentation:
• Feature flag:
• Performance:
• Testing:

Implementation plan

1. Add graphql query:

   {
     groups {
       nodes {
         id
         name
       }
       pageInfo {
         hasNextPage
     		hasPreviousPage
     		startCursor
     		endCursor
       }
     }
   }

2. Add property groupsOnly on component

3. Make sure when groupsOnly is set to true that only groups are loaded

4. Adjust texts accordingly

5. Add tests

Verification steps