Moves GitTestExtensions to Extensions namespace

Relocates `GitTestExtensions` and other related classes to the `GitVersion.Testing.Extensions` namespace for consistent organization. Updates all references and removes the unused `RepositoryFixtureExtensions` class.

Author: arturcic

src/GitVersion.App.Tests/JsonOutputOnBuildServerTest.cs

@@ -1,6 +1,7 @@
 using GitVersion.Agents;
 using GitVersion.Core.Tests;
 using GitVersion.Helpers;
+using GitVersion.Testing.Extensions;
 
 namespace GitVersion.App.Tests;
 

src/GitVersion.App.Tests/PullRequestInBuildAgentTest.cs

@@ -4,6 +4,7 @@
 using GitVersion.Git;
 using GitVersion.Helpers;
 using GitVersion.Output;
+using GitVersion.Testing.Extensions;
 using LibGit2Sharp;
 
 namespace GitVersion.App.Tests;

src/GitVersion.App.Tests/TagCheckoutInBuildAgentTests.cs

@@ -1,6 +1,7 @@
 using GitVersion.Agents;
 using GitVersion.Core.Tests.Helpers;
 using GitVersion.Helpers;
+using GitVersion.Testing.Extensions;
 using LibGit2Sharp;
 
 namespace GitVersion.App.Tests;

src/GitVersion.Core.Tests/Core/GitVersionExecutorTests.cs

@@ -6,6 +6,7 @@
 using GitVersion.Git;
 using GitVersion.Helpers;
 using GitVersion.Logging;
+using GitVersion.Testing.Extensions;
 using GitVersion.VersionCalculation.Caching;
 using LibGit2Sharp;
 using Microsoft.Extensions.DependencyInjection;

src/GitVersion.Core.Tests/Extensions/GitRepositoryTestingExtensions.cs

@@ -5,6 +5,7 @@
 using GitVersion.Git;
 using GitVersion.Helpers;
 using GitVersion.OutputVariables;
+using GitVersion.Testing.Extensions;
 using GitVersion.VersionCalculation;
 using LibGit2Sharp;
 using Microsoft.Extensions.DependencyInjection;

src/GitVersion.Core.Tests/IntegrationTests/BranchWithoutCommitScenarios.cs

@@ -1,4 +1,5 @@
 using GitVersion.Core.Tests.Helpers;
+using GitVersion.Testing.Extensions;
 using LibGit2Sharp;
 
 namespace GitVersion.Core.Tests.IntegrationTests;

src/GitVersion.Core.Tests/IntegrationTests/CreatingAFeatureBranchFromAReleaseBranchScenario.cs

@@ -1,4 +1,5 @@
 using GitVersion.Configuration;
+using GitVersion.Testing.Extensions;
 
 namespace GitVersion.Core.Tests.IntegrationTests;
 

src/GitVersion.Core.Tests/IntegrationTests/DevelopScenarios.cs

@@ -1,5 +1,6 @@
 using GitVersion.Configuration;
 using GitVersion.Core.Tests.Helpers;
+using GitVersion.Testing.Extensions;
 using GitVersion.VersionCalculation;
 using LibGit2Sharp;
 

src/GitVersion.Core.Tests/IntegrationTests/DocumentationSamples.cs

@@ -1,4 +1,5 @@
 using GitVersion.Core.Tests.Helpers;
+using GitVersion.Testing.Extensions;
 
 namespace GitVersion.Core.Tests.IntegrationTests;
 

src/GitVersion.Core.Tests/IntegrationTests/DocumentationSamplesForGitFlow.cs

@@ -1,4 +1,5 @@
 using GitVersion.Configuration;
+using GitVersion.Testing.Extensions;
 using GitVersion.VersionCalculation;
 using LibGit2Sharp;