Upgrade to dotnet 9.0 and application builder

[HarelM]

This updates all the decencies of the server to latest and greatest.
It also changes the application builder of the client side to use modern tools.

[CLAassistant]

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[codecov-commenter]

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Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 90.40%. Comparing base (716b7d1) to head (4d29d49).

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Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2093      +/-   ##
==========================================
- Coverage   90.41%   90.40%   -0.02%     
==========================================
  Files         101      101              
  Lines        8609     8609              
  Branches     1084     1084              
==========================================
- Hits         7784     7783       -1     
- Misses        597      598       +1     
  Partials      228      228              

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