Upgrade to NET 8.

[maliming]

This PR upgrades all ABP templates to the latest .NET 8 version 🚀
After ABP v8.0, all templates now run on .NET 8 🎉
To learn about the new features and enhancements of .NET 8, visit What's new in .NET 8

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (b128006) 51.61% compared to head (7d9a2b9) 51.64%.
Report is 10 commits behind head on dev.

❗ Current head 7d9a2b9 differs from pull request most recent head 3c54cae. Consider uploading reports for the commit 3c54cae to get more accurate results

Additional details and impacted files

@@            Coverage Diff             @@
##              dev   #18142      +/-   ##
==========================================
+ Coverage   51.61%   51.64%   +0.02%     
==========================================
  Files        3058     3058              
  Lines       95843    95843              
  Branches     7644     7644              
==========================================
+ Hits        49472    49494      +22     
+ Misses      44861    44830      -31     
- Partials     1510     1519       +9     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.