Fix and Refactor Scenario Colors

[JonasGilg]

Description

This PR fixes the colorazation of scenarios. Previously a scenario card could have the same color as the case data. There are now two helper functions to fetch the correct colors.

Checklist

I, the author of this PR checked the following requirements for good software quality:

• [x] The code is properly formatted (I ran the formatter)
• [x] The code is written with our software quality standards (I ran the linter)
• [x] The code is written using our code style
• [x] Extensive in source documentation has been added
• [ ] Unit and/or integration tests have been added
• [x] All texts have been internationalized with at least the following languages:
  • [x] English
  • [x] German
• [x] I tried addressing all new accessibility problems displayed in the console and documented if they can't be fixed
• [ ] I attached performance measurements to prevent performance degradation
• [x] I added the changes to the next release section of the changelog

I, the reviewer checked the following things:

• [ ] I ran the software once and tried all new and related functionality to this PR
• [ ] I looked at all new and changed lines of code and commented on possible problems
• [ ] I read the added documentation and checked if it is understandable and clear
• [ ] I checked the added tests for completeness
• [ ] I checked the internationalized strings for spelling errors
• [ ] I checked the performance metrics for problems or unexplained degradation
• [ ] I checked that the changes are noted in the changelog

[github-actions[bot]]

Test Results

39 tests  ±0   39 :white_check_mark: ±0   11s :stopwatch: -1s 17 suites ±0    0 :zzz: ±0   1 files   ±0    0 :x: ±0 

Results for commit 3df619a3. ± Comparison against base commit 3731c3bb.