🐞 Dotnet Unit Tests Use Consistent Assertions

### Is there an existing issue for this?

- [X] I have searched the existing issues

### Current Behavior

some use:

`Assert.That(result, Is.Not.Null);`

instead of `Assert.IsNotNull(result);`

### Expected Behavior

use a consistent format throughout and configure intellisense to highlight it.

https://docs.nunit.org/articles/nunit-analyzers/NUnit2019.html#motivation

### Steps To Reproduce

_No response_

### Environment

```markdown
- OS:
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### Anything else?

_No response_