fix missing helper view

- display the correct path
fix folder in missing plugin
fix folder and error message for missing component
several template correction

- added full path to missing files
- add consistency in displayed error for missing helper, component and behaviors
- fix `config` folder location
- modify the missing datasource config to display the name correctly
Merge pull request #4241 from antograssiot/3.0_missing_template

3.0 template correction