[IMP] compiler: add support for the .translate suffix

Previously, if you wanted to pass a prop and have it be translated, you
had to either to the translation manually in JS, or use a workaround
with t-set and a body so that Owl would translate it for you, and then
pass the t-set variable as a prop. This is quite inconvenient and is a
common use case.

This commit introduces the `.translate` suffix to solve this issue. When
a prop uses this suffix, it is treated as a string instead of a JS
expression, avoiding the need for quotes as well as their escaping and
allowing extraction tools such as babel to generate a clean string as
the term's translation id. This is also more ergonomic. This suffix is
available for both component props and slot props.

This change will still require some work in Odoo to correctly extract
the terms for props using this suffix.

tests/components/slots.test.ts

@@ -179,6 +179,34 @@ describe("slots", () => {
     expect(fixture.innerHTML).toBe("<span>default empty</span>");
   });
 
+  test("can use .translate suffix on slot props", async () => {
+    class Child extends Component {
+      static template = xml`<t t-esc="props.slots.default.message"/>`;
+    }
+
+    class Parent extends Component {
+      static template = xml`<Child><t t-set-slot="default" message.translate="some message"/></Child>`;
+      static components = { Child };
+    }
+
+    await mount(Parent, fixture);
+    expect(fixture.innerHTML).toBe("some message");
+  });
+
+  test(".translate slot props are translated", async () => {
+    class Child extends Component {
+      static template = xml`<t t-esc="props.slots.default.message"/>`;
+    }
+
+    class Parent extends Component {
+      static template = xml`<Child><t t-set-slot="default" message.translate="some message"/></Child>`;
+      static components = { Child };
+    }
+
+    await mount(Parent, fixture, { translateFn: () => "translated message" });
+    expect(fixture.innerHTML).toBe("translated message");
+  });
+
   test("default slot with slot scope: shorthand syntax", async () => {
     let child: any;
     class Child extends Component {