* feat: add support for new variable management functions in Bruno
- Implemented methods to retrieve and delete all environment and global variables.
- Added corresponding translations for new functions in Postman and Bruno converters.
- Updated request handling to include header deletion functionality.
- Enhanced test cases to cover new variable management features.
* feat: add new scripts for environment and global variable management
- Introduced scripts to delete all environment and global variables.
- Added functionality to retrieve all environment and global variables.
- Implemented tests to validate the behavior of new variable management features.
* feat: implement collection variable management in Bruno
- Added methods for managing collection variables: set, get, has, delete, and retrieve all.
- Updated Postman translation functions to reflect new collection variable methods.
- Enhanced tests to validate the functionality of collection variable management.
- Refactored existing code to replace environment variable references with collection variable equivalents.
* feat: enhance collection variable translations in Bruno
- Updated translation functions for collection variable management to align with Postman API.
- Added tests for new collection variable methods: set, has, delete, retrieve all, and clear.
- Refactored existing tests to ensure accurate translation of collection variable operations.
* feat: expand API hints for variable management in Bruno
* fix: test cases
* fix: remove unnecessary return in deleteEnvVar function
