Build Docker image on slim base (#3204)

* Build Docker image on slim base

* Run Playwright tests against Docker container

For Playwright end-to-end tests in CI, instead of running a development
webserver with `yarn dev`, build and deploy a Docker container for
Element Call and use that as the webserver to test against.

* Shut down playwright webserver gracefully

When using a containerized webserver, this stops the container once
tests finish.

* Increase Playwright timeout in CI

---------

Co-authored-by: fkwp <github-fkwp@w4ve.de>

playwright.config.ts

@@ -7,6 +7,10 @@ Please see LICENSE in the repository root for full details.
 
 import { defineConfig, devices } from "@playwright/test";
 
+const baseURL = process.env.USE_DOCKER
+  ? "http://localhost:8080"
+  : "https://localhost:3000";
+
 /**
  * See https://playwright.dev/docs/test-configuration.
  */
@@ -25,7 +29,7 @@ export default defineConfig({
   /* Shared settings for all the projects below. See https://playwright.dev/docs/api/class-testoptions. */
   use: {
     /* Base URL to use in actions like `await page.goto('/')`. */
-    baseURL: "https://localhost:3000",
+    baseURL,
 
     /* Collect trace when retrying the failed test. See https://playwright.dev/docs/trace-viewer */
     trace: "on-first-retry",
@@ -73,9 +77,13 @@ export default defineConfig({
 
   /* Run your local dev server before starting the tests */
   webServer: {
-    command: "yarn dev",
-    url: "https://localhost:3000",
+    command: "./scripts/playwright-webserver-command.sh",
+    url: baseURL,
     reuseExistingServer: !process.env.CI,
     ignoreHTTPSErrors: true,
+    gracefulShutdown: {
+      signal: "SIGTERM",
+      timeout: 500,
+    },
   },
 });