Randomize assembly file names for better concurrency

There is the potential of file collisions when several `PersistentProxy-
Builder`s are used concurrently. Better use a random name fragment in-
stead of a steadily increasing generation count.

Author: stakx

src/Castle.Core/DynamicProxy/PersistentIsolatedTypesModuleScope.cs

@@ -40,7 +40,6 @@ internal sealed class PersistentIsolatedTypesModuleScope : ModuleScope
 		private readonly bool savePhysicalAssemblies;
 		private readonly string outputDirectory;
 
-		private int assemblyCount;
 		private bool usingStrongNamedModule;
 
 		public PersistentIsolatedTypesModuleScope(bool savePhysicalAssemblies = true,
@@ -50,7 +49,6 @@ public PersistentIsolatedTypesModuleScope(bool savePhysicalAssemblies = true,
 			this.savePhysicalAssemblies = savePhysicalAssemblies;
 			this.outputDirectory = outputDirectory ?? Directory.GetCurrentDirectory();
 
-			assemblyCount = 0;
 			usingStrongNamedModule = false;
 		}
 
@@ -99,8 +97,6 @@ internal override Type BuildType(TypeBuilder typeBuilder)
 
 			if (IsAuxiliaryType(typeName) == false)
 			{
-				assemblyCount++;
-
 				var assemblyBuilder = (PersistedAssemblyBuilder)typeBuilder.Assembly;
 
 				using var stream = new MemoryStream();
@@ -110,9 +106,10 @@ internal override Type BuildType(TypeBuilder typeBuilder)
 				{
 					var inStrongNamedModule = type.Module == StrongNamedModule;
 					var assemblyFileName = inStrongNamedModule ? StrongNamedModuleName : WeakNamedModuleName;
+					var randomNameFragment = Guid.NewGuid().ToString("N");
 					assemblyFileName = Path.ChangeExtension(
 						assemblyFileName,
-						string.Concat(".", assemblyCount.ToString(), Path.GetExtension(assemblyFileName)));
+						string.Concat(".", randomNameFragment, Path.GetExtension(assemblyFileName)));
 					var assemblyPath = Path.Combine(outputDirectory, assemblyFileName);
 
 					using var file = File.Open(assemblyPath, FileMode.Create, FileAccess.Write);

src/Castle.Core/DynamicProxy/PersistentProxyBuilder.cs

@@ -60,8 +60,7 @@ public PersistentProxyBuilder() : base(new ModuleScope(true))
 	/// <remarks>
 	///   <para>
 	///     Each assembly will be automatically saved when the proxy type is created.
-	///     Saved assemblies include a generation number in their file names
-	///     (e. g. <c>CastleDynProxy2.{1,2,3,...}.dll</c>) so previous assemblies
+	///     Saved assemblies have partially randomized file names so previous assemblies
 	///     aren't overwritten.
 	///   </para>
 	///   <para>