chore: Removes device code flow support

[steve-calvert-glean]

Code changes:

• Removed device code flow support by deleting relevant functions and handling logic from the code, shifting from an OAuth-based approach to a direct token-based configuration method.

This change indicates a move away from using the device authorization model, which may streamline the configuration process by removing layers of checks and balances associated with OAuth device flows.

Type of Change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Documentation update
• Code refactoring
• Build/CI pipeline changes
• Other (please describe):

How Has This Been Tested?

• Unit tests
• Integration tests
• Manual testing
• Other (please describe):

Checklist

• My code follows the code style of this project
• I have updated the documentation accordingly
• I have added tests to cover my changes
• I have checked for potential breaking changes and addressed them

[david-hamilton-glean]

tests red but otherwise LGTM