Gitpod: wait for postgresql to be listening before startup (#15429)

* Wait for postgresql to be listening on port before setup and startup

 https://github.com/forem/forem/issues/15428 points out an issue where
 the command sequence runs (foreman starts the Procfile.dev)
 but rails exits early because the database is not up.

Await the db port before proceeding.

* Await database in gitpod before starting up

* Move await-port to before: action

see https://www.gitpod.io/docs/config-start-tasks - init is only run
as needed (prebuild, new workspace) once, before is run every time a
workspace starts or restarts.

* When in doubt, sleep

.gitpod.yml

@@ -13,7 +13,10 @@ ports:
 
 tasks:
   - name: Forem Server
-    before: redis-server &
+    before: >
+      redis-server &
+      gp await-port 5432 &&
+      sleep 1
     init: ./gitpod-init.sh
     command: bin/startup
   - name: Open Site