test: gRPC core client init integration test

- Copied the env-variable server from Theia and made it possible to
customize it for the tests. Each test has its own `data` folder.
 - Relaxed the primary package and library index error detection.
This should make the init error detection locale independent.
 - Kill the daemon process subtree when stopping the daemon.

Signed-off-by: Akos Kitta <a.kitta@arduino.cc>

arduino-ide-extension/src/browser/create/create-api.ts

@@ -512,7 +512,7 @@ export class CreateApi {
     const result = await resultProvider(response);
     const parseEnd = performance.now();
     console.debug(
-      `HTTP ${fetchCount} ${method} ${url} [fetch: ${(
+      `HTTP ${fetchCount} ${method}${url} [fetch: ${(
         fetchEnd - fetchStart
       ).toFixed(2)} ms, parse: ${(parseEnd - parseStart).toFixed(
         2