C#: Encode GodotProjectDir as Base64 to prevent issues with special characters

modules/mono/editor/Godot.NET.Sdk/Godot.NET.Sdk/Sdk/Sdk.props

@@ -14,6 +14,7 @@
 
     <GodotProjectDir Condition=" '$(GodotProjectDir)' == '' ">$(MSBuildProjectDirectory)</GodotProjectDir>
     <GodotProjectDir>$([MSBuild]::EnsureTrailingSlash('$(GodotProjectDir)'))</GodotProjectDir>
+    <GodotProjectDirBase64>$([MSBuild]::ConvertToBase64('$(GodotProjectDir)'))</GodotProjectDirBase64>
 
     <!-- Custom output paths for Godot projects. In brief, 'bin\' and 'obj\' are moved to '$(GodotProjectDir)\.godot\mono\temp\'. -->
     <BaseOutputPath>$(GodotProjectDir).godot\mono\temp\bin\</BaseOutputPath>

modules/mono/editor/Godot.NET.Sdk/Godot.SourceGenerators.Sample/Godot.SourceGenerators.Sample.csproj

@@ -7,6 +7,7 @@
   <PropertyGroup>
     <!-- $(GodotProjectDir) would normally be defined by the Godot.NET.Sdk -->
     <GodotProjectDir>$(MSBuildProjectDirectory)</GodotProjectDir>
+    <GodotProjectDirBase64>$([MSBuild]::ConvertToBase64('$(GodotProjectDir)'))</GodotProjectDirBase64>
     <!-- For compiling GetGodotPropertyDefaultValues. -->
     <DefineConstants>$(DefineConstants);TOOLS</DefineConstants>
   </PropertyGroup>

modules/mono/editor/Godot.NET.Sdk/Godot.SourceGenerators/Godot.SourceGenerators.props

@@ -2,6 +2,7 @@
   <ItemGroup>
     <!-- $(GodotProjectDir) is defined by Godot.NET.Sdk -->
     <CompilerVisibleProperty Include="GodotProjectDir" />
+    <CompilerVisibleProperty Include="GodotProjectDirBase64" />
     <CompilerVisibleProperty Include="GodotSourceGenerators" />
     <CompilerVisibleProperty Include="IsGodotToolsProject" />
   </ItemGroup>

modules/mono/editor/Godot.NET.Sdk/Godot.SourceGenerators/ScriptPathAttributeGenerator.cs

@@ -22,10 +22,17 @@ namespace Godot.SourceGenerators
 
             // NOTE: NotNullWhen diagnostics don't work on projects targeting .NET Standard 2.0
             // ReSharper disable once ReplaceWithStringIsNullOrEmpty
-            if (!context.TryGetGlobalAnalyzerProperty("GodotProjectDir", out string? godotProjectDir)
-                || godotProjectDir!.Length == 0)
+            if (!context.TryGetGlobalAnalyzerProperty("GodotProjectDirBase64", out string? godotProjectDir) || godotProjectDir!.Length == 0)
             {
-                throw new InvalidOperationException("Property 'GodotProjectDir' is null or empty.");
+                if (!context.TryGetGlobalAnalyzerProperty("GodotProjectDir", out godotProjectDir) || godotProjectDir!.Length == 0)
+                {
+                    throw new InvalidOperationException("Property 'GodotProjectDir' is null or empty.");
+                }
+            }
+            else
+            {
+                // Workaround for https://github.com/dotnet/roslyn/issues/51692
+                godotProjectDir = Encoding.UTF8.GetString(Convert.FromBase64String(godotProjectDir));
             }
 
             Dictionary<INamedTypeSymbol, IEnumerable<ClassDeclarationSyntax>> godotClasses = context