Add component-factory type to Slint language

Add a type "component-factory" to the Slint language.

internal/compiler/llr/expression.rs

@@ -194,6 +194,7 @@ impl Expression {
         Some(match ty {
             Type::Invalid
             | Type::Callback { .. }
+            | Type::ComponentFactory
             | Type::Function { .. }
             | Type::Void
             | Type::InferredProperty