feat(provideTranslateService): langs

[rbalet]

Current behavior

Actually, to add multiple lang inside the store, we need to do something similar to this

export const appConfig: ApplicationConfig = {
    providers: [
        provideTranslateService({
            fallbackLang: "en",
            loader: provideTranslateHttpLoader({
                prefix: "./i18n/",
                suffix: ".json",
                enforceLoading: true,
            }),
        }),
        provideAppInitializer(() => {
            const translate = inject(TranslateService);
            translate.addLangs(["de", "en"]); // Here
            translate.use("en");
        }),
    ],
};

Expected behavior

Being able to declare it directly inside the provideTranslateService

        provideTranslateService({
            langs: ['de', 'en'] // Here instead
            fallbackLang: "en",
            loader: provideTranslateHttpLoader({
                prefix: "./i18n/",
                suffix: ".json",
                enforceLoading: true,
            }),
        }),

What is the motivation / use case for changing the behavior?

It does reduce the complexity to use the library

Note: not adding lang, then calling use was (from my memory) creating a bug.
This may/will fix this issue also

[CodeAndWeb]

https://ngx-translate.org/reference/configuration/#configuration

lang already exists - it is practically the same as use() in the constructor.

I am not really sure if langs and addLangs() really has a big benefit since it's quite mixed in its use. Loaded languages are added, but you could also add some from the "outside". And it does not restrict the loader from trying to load other languages.
So the only use for this is in a language change dialog, I guess.

[rbalet]

@CodeAndWeb Yes, this isn't as a big of an addition as other issues.

The objective here would only to be able to be able to use the library without having to implement our own logic in a separate service.

As we provide already the addLangs(), it would only be an addition to this.

It could also prepare the following (if wished):

if we decide to go with the persistent storage, we could give the array of langs, and let the library instantiate the language on his own.

The use will then be used to "force" a language to be selected.
The langs first language will be a "fallback" in case no language has been selected.

To be discussed