refactor: replace Moq with Mockolate

[vbreuss]

This PR refactors the testing infrastructure by replacing the Moq mocking framework with Mockolate. The change affects package dependencies and updates test code to use Mockolate's API syntax throughout the codebase.

Key Changes:

• Replaced Moq package dependency with Mockolate version 1.0.0
• Updated test code to use Mockolate's API syntax (Mock.Create, SetupMock, etc.)
• Updated README documentation to reflect the new mocking framework

[Copilot]

Pull request overview

This PR refactors the testing infrastructure by replacing the Moq mocking framework with Mockolate. The change affects package dependencies and updates test code to use Mockolate's API syntax throughout the codebase.

Changes:

• Replaced Moq package dependency with Mockolate version 1.0.0
• Updated test code to use Mockolate's API syntax (Mock.Create, SetupMock, etc.)
• Updated README documentation to reflect the new mocking framework

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 3 comments.

File	Description
Directory.Packages.props	Updated package dependency from Moq 4.20.72 to Mockolate 1.0.0
tests/Directory.Build.props	Replaced Moq package reference with Mockolate
tests/TestableIO.System.IO.Abstractions.Wrappers.Tests/FileSystemTests.cs	Converted all test methods from Moq syntax to Mockolate syntax and added NET6_0 conditional compilation
README.md	Updated mock support documentation examples to use Mockolate instead of Moq

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[github-actions]

Test Results

    31 files  ±0      31 suites  ±0   24s ⏱️ +7s
 1 151 tests ±0   1 150 ✅ ±0    1 💤 ±0  0 ❌ ±0 
11 057 runs  ±0  10 218 ✅ ±0  839 💤 ±0  0 ❌ ±0 

Results for commit 96b53cf. ± Comparison against base commit fc2f666.