Handling of translations

So I finished with the implementation of translations.

Currently, there are three ways of how can we translate flexible descriptions:

1. Using default translate routes so from pages like /flexible-description/{id}/translations, /uk/flexible-description/{id}/translations/add/en/uk
2. Using management form - /admin/structure/manage-flexible-descriptions. Just switch on the desired language and visit this form.
3. Using HTMX form - visit any entity form that supports flexible descriptions and click add/edit description button, flexible descriptions will be handled depending on the current language

About tests: some assertions fail when tests run within ci, but locally it works just fine. Not sure what is the reason for that, increasing delays in waitFor methods didn't help here and the HTML looks fine in the test artifacts.

I added some todo's here so it should be investigated and fixed in the future (I will prepare a separate issue for that).

Automatically closed - issue fixed for 2 weeks with no activity.