Fixed "IsReadonly" for interfaces, traits and enums

[sebastianstucke87]

Fixed \Arkitect\Expression\ForClasses\IsReadonly because:

• interfaces can not be readonly
• traits can not be readonly
• enums can not be readonly
• tests where incorrect

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 94.19%. Comparing base (b78ecce) to head (a4b5f8c).
Report is 3 commits behind head on main.

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Additional details and impacted files

@@            Coverage Diff            @@
##               main     #426   +/-   ##
=========================================
  Coverage     94.19%   94.19%           
- Complexity      582      585    +3     
=========================================
  Files            69       69           
  Lines          1533     1533           
=========================================
  Hits           1444     1444           
  Misses           89       89           

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[AlessandroMinoccheri]

Hi @sebastianstucke87 can you please fix red checks?

[AlessandroMinoccheri]

LGTM 👍