[IMP] runtime: allow using any class as a type in props validation

Previously, we had a fixed whitelist for types that were allowed during
props validation. The implementation however supports using arbitrary
classes, and in practice it's desirable to do so, and already done when
not using typescript (when using typescript, it will error if the class
is not whitelisted), eg in Odoo, we use "Element" for the arch in the
standard view props, but this causes all view controllers to fail type
checking because it's not whitelisted.

This commit simply replaces existing constructors by a generic
constructor type, and adds a test with a validation success and a test
with a validation failure.

tests/components/props_validation.test.ts

@@ -829,6 +829,52 @@ describe("props validation", () => {
     expect(error!).toBeDefined();
     expect(error!.message).toBe("Invalid props for component 'Child': 'message' is missing");
   });
+
+  test("can use custom class as type", async () => {
+    class CustomClass {
+      val = "hey";
+    }
+    class Child extends Component {
+      static props = { customObj: CustomClass };
+      static template = xml`<t t-esc="props.customObj.val"/>`;
+    }
+
+    class Parent extends Component {
+      static components = { Child };
+      static template = xml`<Child customObj="customObj" />`;
+      customObj = new CustomClass();
+    }
+
+    const app = new App(Parent, { test: true });
+    await app.mount(fixture);
+    expect(fixture.innerHTML).toBe("hey");
+  });
+
+  test("can use custom class as type: validation failure", async () => {
+    class CustomClass {}
+    class Child extends Component {
+      static props = { customObj: CustomClass };
+      static template = xml`<div>hey</div>`;
+    }
+
+    class Parent extends Component {
+      static components = { Child };
+      static template = xml`<Child customObj="customObj" />`;
+      customObj = {};
+    }
+
+    const app = new App(Parent, { test: true });
+    let error: OwlError | undefined;
+    const mountProm = app.mount(fixture).catch((e: Error) => (error = e));
+    await expect(nextAppError(app)).resolves.toThrow(
+      "Invalid props for component 'Child': 'customObj' is not a customclass"
+    );
+    await mountProm;
+    expect(error!).toBeDefined();
+    expect(error!.message).toBe(
+      "Invalid props for component 'Child': 'customObj' is not a customclass"
+    );
+  });
 });
 
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