Fix enabled feature flags object composition (#2899)

### Motivation

I made a mistake when mapping the feature flags into an object. They are supposed to be a hash like object and not an array.

### Implementation

Used `Object.fromEntries` to build the hash.

vscode/src/client.ts

@@ -52,12 +52,9 @@ interface ServerErrorTelemetryEvent {
 
 type ServerTelemetryEvent = ServerErrorTelemetryEvent;
 
-function enabledFeatureFlags() {
+function enabledFeatureFlags(): Record<string, boolean> {
   const allKeys = Object.keys(FEATURE_FLAGS) as (keyof typeof FEATURE_FLAGS)[];
-
-  return allKeys.map((key) => {
-    return { [key]: featureEnabled(key) };
-  });
+  return Object.fromEntries(allKeys.map((key) => [key, featureEnabled(key)]));
 }
 
 // Get the executables to start the server based on the user's configuration