Visual Studio 2019 Support

[Danielku15]

This PR provides a VS2019 compatible version of the VS Start page. #41

• [x] Create logic for patching the Quick Start Window
• [x] Restructure the UI and inject BetterStartPage
• [x] Port the File > Open Favourite Menu to VS 2019
• [x] Avoid duplicate opening of start page in case startup is not set to "Empty environment"
• [x] Fix dialog misplacement in case startup is not set to "Empty environment"
• [x] Adopt VS 2019 Styles
• [x] Fix UI disturbances (border caused by resizable window)
• [x] Center Quick Start Menu on launch #
• [x] New Large/Small Display Mode
• [x] Clean warnings
• [ ] Polishing on the dialogs
• [ ] Rework code to also provide old VS support.