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/server.start.sh

@@ -0,0 +1,66 @@
+#!/bin/bash
+set -e -u -o pipefail
+cd $(dirname $0)
+. .e2erc
+
+export BRANCH_DEFAULT=$(git branch --show-current)
+export BRANCH=${BRANCH:-$BRANCH_DEFAULT}
+export BUILD_ID_DEFAULT=$(date +%s)
+export BUILD_ID=${BUILD_ID:-$BUILD_ID_DEFAULT}
+export CI_BASE_URL="${CI_BASE_URL:-localhost}"
+
+# Cleanup old containers, if any
+mme2e_log "Stopping leftover E2E containers, if any are running"
+${MME2E_DC_SERVER} down -v
+
+# Generate .env.server
+mme2e_log "Generating .env.server"
+mme2e_generate_envfile_from_var_names >.env.server <<EOF
+MM_LICENSE
+EOF
+envarr=$(echo ${MM_ENV:-} | tr "," "\n")
+for env in $envarr; do
+  echo "$env" >> .env.server
+done
+
+# Generate .env.cypress
+mme2e_log "Generating .env.cypress"
+mme2e_generate_envfile_from_var_names >.env.cypress <<EOF
+BRANCH
+BUILD_ID
+CI_BASE_URL
+AUTOMATION_DASHBOARD_URL
+AUTOMATION_DASHBOARD_TOKEN
+EOF
+
+# Wait for the required server image
+mme2e_log "Waiting for server image to be available"
+mme2e_wait_image ${SERVER_IMAGE} 30 60
+
+# Create the containers and generate the server config
+mme2e_log "Creating E2E containers and generating server config"
+${MME2E_DC_SERVER} create
+${MME2E_DC_SERVER} up -d -- utils
+${MME2E_DC_SERVER} exec -T -w /opt/mattermost-server/server -- utils bash <<EOF
+apt update && apt install -y jq
+OUTPUT_CONFIG=/tmp/config_generated.json go run scripts/config_generator/main.go
+jq "
+  .ServiceSettings.SiteURL=\"http://server:8065\"
+| .PluginSettings.Enable=true
+| .PluginSettings.EnableUploads=true
+| .PluginSettings.AutomaticPrepackagedPlugins=true
+| .TeamSettings.EnableOpenServer=true
+| .ElasticsearchSettings.ConnectionURL=\"http://elasticsearch:9200\"
+" </tmp/config_generated.json >/opt/server-config/config.json
+echo "### Generated server config:"
+cat /opt/server-config/config.json
+EOF
+
+# Launch mattermost-server, and wait for it to be healthy
+mme2e_log "Starting E2E containers"
+${MME2E_DC_SERVER} up -d
+if ! mme2e_wait_service_healthy server 60 10; then
+  mme2e_log "Mattermost container not healthy, retry attempts exhausted. Giving up." >&2
+  exit 1
+fi
+mme2e_log "Mattermost container is running and healthy"