Couple bug fixes - exists with case sensitivity and primitive != operator

[moxplod]

Description

Fixed couple issues one involving case in-sensitivity logic. One involving primitives.

Fixes # #204
#202

Type of change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)

Checklist

• I have performed a self-review of my code
• I have added tests that prove my fix is effective or that my feature works
• I have made corresponding changes to the documentation
• I have commented my code, particularly in hard-to-understand areas
• New and existing unit tests pass locally with my changes

[what-the-diff]

PR Summary

• Enhanced Code Safety in BaseQueryBuilder
  Null check added to string value in src/Gridify/Builder/BaseQueryBuilder.cs. This prevents potential crashes when certain data is not available.

• Improved Reliability in LinqQueryBuilder
  Added a null check to the Not Contains expression in src/Gridify/Builder/LinqQueryBuilder.cs. This ensures that the software continues to function correctly even if unexpected situations arise.

• Extended Sample Data For Testing
  New data item was added to the sample data in test/Gridify.Tests/GridifyExtensionsShould.cs. This helps in testing more scenarios and ensuring the robustness of the application.

• Added New Test Cases For Identified Issues
  New test scenarios have been added in test/Gridify.Tests/IssueTests/Issue202Tests.cs and test/Gridify.Tests/IssueTests/Issue204Tests.cs. These will allow us to be confident that these specific issues have been dealt with correctly and will not reoccur in the future.

[alirezanet]

LGTM 👌💐

[moxplod]

@alirezanet Great, please merge it when you can. I do not have permissions to.