Add StartProxyConnectionChecks feature

src/feature-flags.ts

@@ -72,6 +72,7 @@ export enum Feature {
   QaTelemetryEnabled = "qa_telemetry_enabled",
   /** Note that this currently only disables baseline file coverage information. */
   SkipFileCoverageOnPrs = "skip_file_coverage_on_prs",
+  StartProxyConnectionChecks = "start_proxy_connection_checks",
   UploadOverlayDbToApi = "upload_overlay_db_to_api",
   UseRepositoryProperties = "use_repository_properties",
   ValidateDbConfig = "validate_db_config",
@@ -297,6 +298,11 @@ export const featureConfig = {
     // cannot be found when interpreting results.
     minimumVersion: undefined,
   },
+  [Feature.StartProxyConnectionChecks]: {
+    defaultValue: false,
+    envVar: "CODEQL_ACTION_START_PROXY_CONNECTION_CHECKS",
+    minimumVersion: undefined,
+  },
   [Feature.UploadOverlayDbToApi]: {
     defaultValue: false,
     envVar: "CODEQL_ACTION_UPLOAD_OVERLAY_DB_TO_API",