Add an 'enable' flag in the server configuration to enable gql-based searches

"extensions": {
        "search": {
            "enable": true
        }
    }

pkg/cli/cve_cmd_test.go

@@ -308,7 +308,8 @@ func TestServerCVEResponse(t *testing.T) {
 		UpdateInterval: 2,
 	}
 	searchConfig := &ext.SearchConfig{
-		CVE: cveConfig,
+		CVE:    cveConfig,
+		Enable: true,
 	}
 	c.Config.Extensions = &ext.ExtensionConfig{
 		Search: searchConfig,

pkg/cli/image_cmd_test.go

@@ -287,7 +287,7 @@ func TestServerResponse(t *testing.T) {
 		config := api.NewConfig()
 		config.HTTP.Port = port
 		config.Extensions = &extensions.ExtensionConfig{
-			Search: &extensions.SearchConfig{},
+			Search: &extensions.SearchConfig{Enable: true},
 		}
 		c := api.NewController(config)
 		dir, err := ioutil.TempDir("", "oci-repo-test")