Updated bootstrapper script (#436)

Streamlined Installation Process: Simplified the installation of PowerShell for the Harden Windows Security module and AppControl Manager, making it easier to review and comprehend. This update reduces the codebase by 170 lines.

Improved Security and Logic: the AppControl function no longer generates a PFX file. Instead, the private key is now configured as non-exportable from the outset, aligning with the native logic implemented in AppControl Manager.

Added more useful comments to the code.

AppControl function now supports full offline support so if you download the AppControl Manager's MSIX file from GitHub or build it form source code yourself, and have signtool.exe locally available, you can install it in a complete offline environment.