Replace current UpdateOfferView with Framework for new GridLayout (#944)

[Steffengreiner]

This PR aims to replace the current Stepper based implementation for the Update Offer View with a Grid based View as outlined here :

This will be done iteratively with seperate PRs:

• Establish general structure of GridLayout and provide dummy views Replace current UpdateOfferView with Framework for new GridLayout #944
• Implement Project Information Layout and wire ViewModel Logic necessary for ProjectInformationView Implement ProjectInformationLayout #943
• Implement Project Manager Layout and wire ViewModel Logic necessary for ProjectManagerView Implement Logic for CustomerLayout and ProjectManager in UpdateOfferView #945
• Implement Update Customer Layout and wire ViewModel Logic necessary for CustomerView Implement Logic for CustomerLayout and ProjectManager in UpdateOfferView #945
• Implement SelectItems Layout and wire ViewModel Logic necessary for SelectItemsView
• Provide Costcalculation Logic from Items in SelectItems Layout
• Save and Cancel Offer Update Process with Reset Logic.