Improve feedback to the user about protection measures
**1. Show a loading bar over the sector when a protection measure is being built**
* [x] Create Billboard graphics (LFI)
* [x] Implement loading bar (ITC)
* [x] Fix Loading bar prefabs (LFI)
**2. Show loading bar at the sector statistics display**
* [x] Implement loading bar (ITC)
**3. Block the action that is already implemented for the respective sector as long as the protection is in effect**
* [x] Change button behaviour (ITC)
**4. Show effectiveness of each protection on the respective sector statistics display when it is in effect**
* [x] Implement loading bar behaviour in sector statistics display (ITC)
**5. Visually change the sector on which protections are in effect**
* [x] Create Model/Texture/Button for "green roofs" (LFI)
* [x] Create Model/Texture/Button for "multipurpose areas" (LFI)
* [x] Create Model/Texture/Button for "unsealed surfaces" (LFI)
* [x] Create Model/Texture/Button "distribute sandbags" (LFI)
* [x] Create Model/Texture/Button "improve sewer system" (LFI)
* [x] Create Model/Texture/Button "stormwater planters" (LFI)
* [x] Create Model/Texture/Button "activate mobile gates" (LFI)
* [x] Create Model/Texture/Button "closing underground parkings" (LFI)
* [x] Create Model/Texture/Button "closing streets" (LFI)
* [x] Create Healthbar for "inform the public" (LFI)
* [x] Implement the visual changes (ITC)
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