Implement Navigation

[devtobi]

• [x] Implement Navigation using AutoRoute
• [x] Implement Custom BottomBar Widget
• [x] Implement Navigation Logic to all empty screens
• [x] Implement Wrapper for all Pages
• [x] Implement Bloc for Navigation (optional) (not needed)

[devtobi]

Finished the bottom_navigation_bar and custom_scaffold widgets. TODO After merge to develop:

• Add route to history screen
• Add route for workout fab to workout screen

[devtobi]

The logic has been implemented and has to be adopted to upcoming screens from other branches.