Add Esperanto language to language filter

[jorgesumle]

You cannot select the Esperanto language when filtering instances, but https://esperanto.masto.host/ is an Esperanto-speaking instance, as they state:

This is an Esperanto-speaking instance, so it goes without saying that users are expected to toot in Esperanto. There are a million other instances to create your account if you intend to toot in English or any other language.

In addition, it would be nice if you could review #316. If translations need to be added via Crowdin, admins should add Esperanto. I've contacted them requesting Esperanto, but I'm still waiting.