Import organizing and formatting on code generation

[jfaltermeier]

We should do this on save after code generation.
The current code generation cannot perform this on server side, because the clean up actions require UI for some reason.

[jfaltermeier]

https://github.com/theia-ide/theia/blob/5336443c48e75152f587c1221af8c9e6932415e0/packages/java/src/browser/java-commands.ts

shows how the import organizing works in theia. On our side, I think we may add something similar in smart-home-editor-frontend-module.ts in the MyResourceSaveable, where could override save() to get a hook once a save is done.

Other option would be to directly add it to the code-generator.ts