make the DtoGenerator is compatible with ImplicitUsings=false

[baoduy]

This pull request primarily introduces global using directives to simplify code and removes redundant using statements from multiple files. Additionally, it makes minor project configuration updates for clarity and consistency.

Global Usings and Code Cleanup:

• Added a GlobalUsings.cs file in DKNet.EfCore.DtoEntities to centralize common using directives, and removed now-redundant using statements from many entity and shared files. [1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [11] [12] [13] [14]

• Added a GlobalUsings.cs file for test projects to centralize test-related using directives.

Project Configuration Improvements:

• Set <ImplicitUsings>false</ImplicitUsings> in both DKNet.EfCore.DtoEntities.csproj and EfCore.DtoGenerator.Tests.csproj to disable automatic implicit usings, ensuring that only explicitly defined or global usings are used. [1] [2]

• Minor formatting and consolidation of MSBuild XML in EfCore.DtoGenerator.Tests.csproj for improved readability. [1] [2]

Other Minor Changes:

• Added missing using System; in GenerateDtoAttribute.cs.
• Minor whitespace addition to Order.cs.

[github-actions]

📊 Code Coverage Report

| Metric | Coverage |
|--------|----------|
| **Line Coverage** | 87.7% |
| **Branch Coverage** | 80.4% |
| **Method Coverage** | 85.9% |

**Lines:** 3257/undefined covered
**Branches:** 1209/undefined covered

📈 [View Full Coverage Report](https://github.com/baoduy/DKNet/actions/runs/27936416657)

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 84.13%. Comparing base (8e08990) to head (09aeacd).
⚠️ Report is 3 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #304      +/-   ##
==========================================
- Coverage   84.15%   84.13%   -0.03%     
==========================================
  Files         159      159              
  Lines        3712     3712              
  Branches      574      574              
==========================================
- Hits         3124     3123       -1     
  Misses        412      412              
- Partials      176      177       +1     

Flag	Coverage Δ
unittests	84.13% <ø> (-0.03%)	⬇️

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