…ronment variable at the initial creation.

1. Set the User's default language based on LANG;
2. Set the Knowledgebase's default language based on LANG; 
3. Set the default language of the Dialog based on LANG;

### What problem does this PR solve?

_Briefly describe what this PR aims to solve. Include background context
that will help reviewers understand the purpose of the PR._

### Type of change

- [ ] Bug Fix (non-breaking change which fixes an issue)
- [ ] New Feature (non-breaking change which adds functionality)
- [ ] Documentation Update
- [ ] Refactoring
- [ ] Performance Improvement
- [ ] Other (please describe):