chore : Improved testing and feature enhancements for public sharing

[nfebe]

This update enhances the testing framework for public sharing by improving the setup and management of share contexts. It refactors the code to make the createShare function reusable externally, ensuring better testability and flexibility. Additionally, the update optimizes share permission adjustments and improves state management, making public share setups more efficient and maintainable.

Adds the following tests:

• Checks if user can see enforced expiry date before link share is created
• Checks if user can see non-enforced default expiry before share is created