Use HashCode.Combine() in interop source generators and analyzers instead of custom GetHashCode implementations

src/libraries/System.Runtime.InteropServices/gen/ComInterfaceGenerator/ComInterfaceInfo.cs

@@ -191,8 +191,8 @@ private static bool TryGetGuid(INamedTypeSymbol interfaceSymbol, InterfaceDeclar
 
         public override int GetHashCode()
         {
-            // ContainingSyntax and ContainingSyntaxContext do not implement GetHashCode
-            return HashCode.Combine(Type, TypeDefinitionContext, InterfaceId);
+            // ContainingSyntax does not implement GetHashCode
+            return HashCode.Combine(Type, ThisInterfaceKey, BaseInterfaceKey, TypeDefinitionContext, InterfaceId);
         }
 
         public bool Equals(ComInterfaceInfo other)

src/libraries/System.Runtime.InteropServices/gen/Microsoft.Interop.SourceGeneration/ContainingSyntaxContext.cs

@@ -79,7 +79,7 @@ public override int GetHashCode()
             int code = ContainingNamespace?.GetHashCode() ?? 0;
             foreach (ContainingSyntax containingSyntax in ContainingSyntax)
             {
-                code ^= containingSyntax.Identifier.Value.GetHashCode();
+                code = HashCode.Combine(code, containingSyntax.Identifier.Value);
             }
             return code;
         }

src/libraries/System.Runtime.InteropServices/gen/Microsoft.Interop.SourceGeneration/ManagedTypeInfo.cs

@@ -25,7 +25,7 @@ public virtual bool Equals(ManagedTypeInfo? other)
 
         public override int GetHashCode()
         {
-            return FullTypeName.GetHashCode() ^ DiagnosticFormattedName.GetHashCode();
+            return HashCode.Combine(FullTypeName, DiagnosticFormattedName);
         }
 
         protected ManagedTypeInfo(ManagedTypeInfo original)

src/libraries/System.Runtime.InteropServices/gen/Microsoft.Interop.SourceGeneration/ManualTypeMarshallingHelper.cs

@@ -37,7 +37,7 @@ public override int GetHashCode()
             int hash = 0;
             foreach (KeyValuePair<MarshalMode, CustomTypeMarshallerData> mode in Modes)
             {
-                hash ^= mode.Key.GetHashCode() ^ mode.Value.GetHashCode();
+                hash = HashCode.Combine(hash, mode.Key, mode.Value);
             }
             return hash;
         }