[dev] Devcontainer tweak (#9092)

* Remove blocking steps from devcontainer setup

* Ensure postCreateCommand.sh fails

* Mount postgres db to separate dir

- Avoid ownership issues of 'dev' dir

* Bump devcontainer docs

.gitignore

@@ -81,6 +81,7 @@ js_tmp/
 
 # Development files
 dev/
+dev-db/
 data/
 env/