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

---------

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/cypress/package-lock.json

@@ -1,5 +1,5 @@
 {
-  "name": "cypress",
+  "name": "app",
   "lockfileVersion": 2,
   "requires": true,
   "packages": {

e2e-tests/cypress/tests/support/index.js

@@ -216,6 +216,9 @@ function sysadminSetup(user) {
     // # Deactivate test bots if any
     cy.apiDeactivateTestBots();
 
+    // # Disable welcome tours if any
+    cy.apiDisableTutorials(user.id);
+
     // # Check if default team is present; create if not found.
     cy.apiGetTeamsForUser().then(({teams}) => {
         const defaultTeam = teams && teams.length > 0 && teams.find((team) => team.name === DEFAULT_TEAM.name);