feat: Add iPad support & adapt calendar

Week 10 -

• Add application icons.
• Fix LaunchScreen constraints for iPad & iPhone 7
• Add year view for iPad
• Modify Segmented control of calendar type for iPad
• Modify navigationViewStyle for iPad
• Modify calendar view top gradient background to change according to calendar type
• Fix iPad Calendar view spacing
• Set navigationViewStyle based on device
• Modify Settings View for iPad

Closes #30 (closed)

UI Changes:

iPad:

Calendar View

iPhone Settings View