Fix port availability test

Problem raised on macOS where port 49152 was used by rapportd process
listening on 0.0.0.0 address and as a consequence the application proxy
server wasn't correctly setup that in turn disrupted the webview display
that wasn't served through http://<uid>.localhost:49152/ (#255)

Indeed the checkPort() function was checking port availability using the
127.0.0.1 address that doesn't error.

The minimal fix here is to test port availability using 0.0.0.0 address.

Signed-off-by: Alexis Deruelle <alexis.deruelle@gmail.com>

src/main/port.ts

@@ -9,7 +9,7 @@ function checkPort(port: number) {
     server
       .on('error', error => reject(error))
       .on('listening', () => server.close(() => resolve(port)))
-      .listen({host: "127.0.0.1", port: port}))
+      .listen({host: "0.0.0.0", port: port}))
 }
 
 export async function getFreePort(firstPort: number, lastPort: number): Promise<number> {