CLD-5698 - Add e2e smoketests (#23590)

* Prepare: run E2E smoketests with GitHub actions (#23301)
* Port E2E testing scripts from cypress-ui-automation
* Move server to docker-compose, move E2E images to ecrpublic
* Integrate General channel renaming, fixes
* Add local automation-dashboard
 Add readme
* Add E2E smoketests
* Bump postgres to 12
* Fully rely on mattermostdevelopment images

---------

Co-authored-by: Mattermost Build <build@mattermost.com>
Co-authored-by: Saturnino Abril <saturnino.abril@gmail.com>
Co-authored-by: Antonis Stamatiou <stamatiou.antonis@gmail.com>

e2e-tests/.ci/dashboard.stop.sh

@@ -0,0 +1,11 @@
+#!/bin/bash
+set -e -u -o pipefail
+cd $(dirname $0)
+. .e2erc
+
+if [ -d dashboard ]; then
+  mme2e_log "Stopping the dashboard containers"
+  ${MME2E_DC_DASHBOARD} down
+else
+  mme2e_log "Not stopping the dashboard containers: dashboard repo not checked out locally, skipping"
+fi