Ensure all quick picks have a way to exit (back button)

[cwebster-99]

Observed in user studies that users were unable to exit quick picks at certain times / not all of them had back buttons. We should do an audit of these.

They had to be prompted to his esc - there is also a VS Code setting for this but I dont think it is default

[eleanorjboyd]

Added back button support to multi-step UI flows
Problem: The UI flows for environment creation and Python project setup lacked back button functionality, forcing users to cancel and restart when they needed to change a previous selection.

Steps to verify fix:

1. Test back button in PET workflow: Run "Python Environments: Run Python Environment Tool in Terminal", select "Resolve Environment...", press back button, confirm it returns to menu
2. Test back button in VENV creation: Run "Create environment", select VENV, press back button at various steps
3. Test back button in CONDA creation: Create CONDA environment, use back buttons to navigate between steps
4. Test back button in Python project flow: Add Python project, verify back functionality in project type selection