Pronouns: add support for PronounDB.org

[TheTaraStark]

PronounDB.org offers clearer user-side AI and supports multiple websites outside Twitch.

They also offer a clean and well-documented API.

On how to handle conflict when PronounDB and pronouns.alejo.io both return results: my recommendation would be to let broadcaster choose priority in widget settings, but I'm open to other ideas.

[zaytri]

would likely just have it prioritize Alejo pronouns first since it covers more pronoun options (includes neopronouns)

also seems like their API only provides the subject form of each pronoun, not the object form, so would need to hardcode that in

it's a reasonable request since some people use PronounDB instead