Improve feedback to the user about protection measures

1. Show a loading bar over the sector when a protection measure is being built

• Create Billboard graphics (LFI)
• Implement loading bar (ITC)
• Fix Loading bar prefabs (LFI)

2. Show loading bar at the sector statistics display

• Implement loading bar (ITC)

3. Block the action that is already implemented for the respective sector as long as the protection is in effect

• Change button behaviour (ITC)

4. Show effectiveness of each protection on the respective sector statistics display when it is in effect

• Implement loading bar behaviour in sector statistics display (ITC)

5. Visually change the sector on which protections are in effect

• Create Model/Texture/Button for "green roofs" (LFI)
• Create Model/Texture/Button for "multipurpose areas" (LFI)
• Create Model/Texture/Button for "unsealed surfaces" (LFI)
• Create Model/Texture/Button "distribute sandbags" (LFI)
• Create Model/Texture/Button "improve sewer system" (LFI)
• Create Model/Texture/Button "stormwater planters" (LFI)
• Create Model/Texture/Button "activate mobile gates" (LFI)
• Create Model/Texture/Button "closing underground parkings" (LFI)
• Create Model/Texture/Button "closing streets" (LFI)
• Create Healthbar for "inform the public" (LFI)
• Implement the visual changes (ITC)