Add instance dashboard graphql queries/mutations

- get projects for instance security dashboard
- get projects by search term
- add project
- remove projects

ee/app/assets/javascripts/security_dashboard/graphql/add_project_to_security_dashboard.mutation.graphql

+mutation addProjectToSecurityDashboard($id: ID!) {
+  addProjectToSecurityDashboard(input: {id: $id}) {
+    errors
+  }
+}

ee/app/assets/javascripts/security_dashboard/graphql/delete_project_from_security_dashboard.mutation.graphql

+mutation deleteProjectFromSecurityDashboard($id: ID!) {
+  removeProjectFromSecurityDashboard(input: {id: $id}) {
+    errors
+  }
+}

ee/app/assets/javascripts/security_dashboard/graphql/get_instance_security_dashboard_projects.query.graphql

+query getInstanceSecurityDashboardProjects {
+  instanceSecurityDashboard {
+    projects {
+      nodes {
+        id
+        name
+      }
+    }
+  }
+}

ee/app/assets/javascripts/security_dashboard/graphql/get_projects.query.graphql

+query getProjects($search: String!) {
+  projects(search: $search, membership: true) {
+    nodes {
+      id
+      name
+    }
+  }
+}