Add icon parameter for tools.

[uhafner]

Refactor icon handling:

1. check the icon of the tool
2. check the specific icon in the registry
3. check the icon of the configuration
4. dallback: default icon of markdown class

[codecov]

Codecov Report

Attention: Patch coverage is 90.09901% with 10 lines in your changes missing coverage. Please review.

Please upload report for BASE (main@1e83231). Learn more about missing BASE report.
Report is 2 commits behind head on main.

Files with missing lines	Patch %	Lines
...main/java/edu/hm/hafner/grading/CoverageScore.java	76.47%	3 Missing and 1 partial ⚠️
...n/java/edu/hm/hafner/grading/CoverageMarkdown.java	57.14%	2 Missing and 1 partial ⚠️
.../hafner/grading/FileSystemMetricReportFactory.java	0.00%	1 Missing ⚠️
.../main/java/edu/hm/hafner/grading/TestMarkdown.java	93.33%	0 Missing and 1 partial ⚠️
src/main/java/edu/hm/hafner/grading/TestScore.java	88.88%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #391   +/-   ##
=======================================
  Coverage        ?   85.79%           
  Complexity      ?      478           
=======================================
  Files           ?       30           
  Lines           ?     1401           
  Branches        ?       82           
=======================================
  Hits            ?     1202           
  Misses          ?      167           
  Partials        ?       32           

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[github-actions]

☀️   Quality Monitor

   🚦   Tests: 100 % successful (✔️ 162 passed)
   〰️   Line Coverage: 88% (167 missed lines)
   ➰   Branch Coverage: 85% (58 missed branches)
     Mutation Coverage: 78% (169 survived mutations)
   🔬   Test Strength: 88% (85 survived mutations in tested code)
     CheckStyle: No warnings
     PMD: No warnings
     SpotBugs: No bugs
   🐛   Error Prone: No bugs
     OWASP Dependency Check: 1 vulnerability (normal: 1)
   🌀   Cyclomatic Complexity: 567
   💡   Cognitive Complexity: 226
   📝   Non Commenting Source Statements: 1998
   ➿   N-Path Complexity: 1046

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Created by Quality Monitor v1.12.0 (#910ef11). More details are shown in the GitHub Checks Result.