feat: add minimal devcontainer setup (#14038)

* add minimal devcontainer setup

* fix Makefile & update doc

* fix Makefile

* add warning regarding devcontainer + add newline at EOF

docs/docs/developer/pr-checklist.md

@@ -1,5 +1,9 @@
 # PR Checklist
 
+A minimal devcontainer is supplied with this repository. All commands can be executed directly inside this container to avoid tedious installation of the environment.
+:::warning
+The provided devcontainer isn't complete at the moment. At least all dockerized steps in the Makefile won't work (`make dev`, ....). Feel free to contribute!
+:::
 When contributing code through a pull request, please check the following:
 
 ## Web Checks