Python: Expose Slint structs

Structs declared and exported in Slint are now available in the module namespace
with a constructor.

Fixes #5708

api/python/tests/test_load_file.py

@@ -12,14 +12,22 @@ def test_load_file(caplog):
 
     assert "The property 'color' has been deprecated. Please use 'background' instead" in caplog.text
 
-    assert len(list(module.__dict__.keys())) == 2
+    assert len(list(module.__dict__.keys())) == 3
     assert "App" in module.__dict__
     assert "Diag" in module.__dict__
+    assert "MyData" in module.__dict__
     instance = module.App()
     del instance
     instance = module.Diag()
     del instance
 
+    struct_instance = module.MyData()
+    struct_instance.name = "Test"
+    struct_instance.age = 42
+
+    struct_instance = module.MyData(name="testing")
+    assert struct_instance.name == "testing"
+
 
 def test_load_file_fail():
     with pytest.raises(CompileError, match="Could not compile non-existent.slint"):

api/python/tests/test_load_file.slint

@@ -13,6 +13,11 @@ export global SecondGlobal {
     out property <string> second: "second";
 }
 
+export struct MyData {
+    name: string,
+    age: int
+}
+
 export component App inherits Window {
     in-out property <string> hello: "World";
     callback say-hello(string) -> string;