[SPA] Adds Keep-Alive header to avoid console errors on Mac and Linux (#28)

The HPM proxy sends Connection: close headers and that results in Kestrel closing the connection and the proxy failing.

src/content/Angular-CSharp/ClientApp/proxy.conf.js

@@ -17,7 +17,10 @@ const PROXY_CONFIG = [
 //#endif
    ],
     target: target,
-    secure: false
+    secure: false,
+    headers: {
+      Connection: 'Keep-Alive'
+    }
   }
 ]
 

src/content/React-CSharp/ClientApp/src/setupProxy.js

@@ -19,7 +19,10 @@ const context =  [
 module.exports = function(app) {
   const appProxy = createProxyMiddleware(context, {
     target: target,
-    secure: false
+    secure: false,
+    headers: {
+      Connection: 'Keep-Alive'
+    }
   });
 
   app.use(appProxy);