Upgrade to C# 12, net10.0, and modernize codebase

Modernized code to use C# 12 features (collection expressions, raw string literals, `field` keyword), refactored extension methods for `ReadOnlySpan<char>`, and improved enum utilities. Updated all project and test files to target net10.0 and upgraded NuGet dependencies. Enhanced analyzers and code fixes with modern idioms, improved test consistency, and performed general code cleanup. Bumped package version to 10.0.0 for major changes.

Author: electricessence

Analyzers.Tests/Open.Text.Analyzers.Tests.csproj

@@ -9,17 +9,17 @@
   </PropertyGroup>
 
   <ItemGroup>
-    <PackageReference Include="Microsoft.CodeAnalysis.CSharp" Version="4.8.0" />
-    <PackageReference Include="Microsoft.CodeAnalysis.CSharp.Workspaces" Version="4.8.0" />
-    <PackageReference Include="Microsoft.CodeAnalysis.CSharp.Analyzer.Testing.XUnit" Version="1.1.1" />
-    <PackageReference Include="Microsoft.CodeAnalysis.CSharp.CodeFix.Testing.XUnit" Version="1.1.1" />
-    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.8.0" />
-    <PackageReference Include="xunit" Version="2.6.2" />
-    <PackageReference Include="xunit.runner.visualstudio" Version="2.5.4">
+    <PackageReference Include="Microsoft.CodeAnalysis.CSharp" Version="5.0.0" />
+    <PackageReference Include="Microsoft.CodeAnalysis.CSharp.Workspaces" Version="5.0.0" />
+    <PackageReference Include="Microsoft.CodeAnalysis.CSharp.Analyzer.Testing.XUnit" Version="1.1.2" />
+    <PackageReference Include="Microsoft.CodeAnalysis.CSharp.CodeFix.Testing.XUnit" Version="1.1.2" />
+    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="18.0.1" />
+    <PackageReference Include="xunit" Version="2.9.3" />
+    <PackageReference Include="xunit.runner.visualstudio" Version="3.1.5">
       <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
       <PrivateAssets>all</PrivateAssets>
     </PackageReference>
-    <PackageReference Include="coverlet.collector" Version="6.0.0">
+    <PackageReference Include="coverlet.collector" Version="6.0.4">
       <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
       <PrivateAssets>all</PrivateAssets>
     </PackageReference>