fix(core): move generated i18n statements to the consts field of ComponentDef (#38404)

This commit updates the code to move generated i18n statements into the `consts` field of
ComponentDef to avoid invoking `$localize` function before component initialization (to better
support runtime translations) and also avoid problems with lazy-loading when i18n defs may not
be present in a chunk where it's referenced.

Prior to this change the i18n statements were generated at the top leve:

```
var I18N_0;
if (typeof ngI18nClosureMode !== "undefined" && ngI18nClosureMode) {
    var MSG_X = goog.getMsg(“…”);
    I18N_0 = MSG_X;
} else {
    I18N_0 = $localize('...');
}

defineComponent({
    // ...
    template: function App_Template(rf, ctx) {
        i0.ɵɵi18n(2, I18N_0);
    }
});
```

This commit updates the logic to generate the following code instead:

```
defineComponent({
    // ...
    consts: function() {
        var I18N_0;
        if (typeof ngI18nClosureMode !== "undefined" && ngI18nClosureMode) {
            var MSG_X = goog.getMsg(“…”);
            I18N_0 = MSG_X;
        } else {
            I18N_0 = $localize('...');
        }
        return [
            I18N_0
        ];
    },
    template: function App_Template(rf, ctx) {
        i0.ɵɵi18n(2, 0);
    }
});
```

Also note that i18n template instructions now refer to the `consts` array using an index
(similar to other template instructions).

PR Close #38404

packages/core/src/render3/interfaces/node.ts

@@ -255,9 +255,24 @@ export type TAttributes = (string|AttributeMarker|CssSelector)[];
  * Constants that are associated with a view. Includes:
  * - Attribute arrays.
  * - Local definition arrays.
+ * - Translated messages (i18n).
  */
 export type TConstants = (TAttributes|string)[];
 
+/**
+ * Factory function that returns an array of consts. Consts can be represented as a function in case
+ * any additional statements are required to define consts in the list. An example is i18n where
+ * additional i18n calls are generated, which should be executed when consts are requested for the
+ * first time.
+ */
+export type TConstantsFactory = () => TConstants;
+
+/**
+ * TConstants type that describes how the `consts` field is generated on ComponentDef: it can be
+ * either an array or a factory function that returns that array.
+ */
+export type TConstantsOrFactory = TConstants|TConstantsFactory;
+
 /**
  * Binding data (flyweight) for a particular node that is shared between all templates
  * of a specific type.