plugin for LipSurf to enable hands-free reviews on Bunpro

relies on support implemented by the Bunpro developers:

> There is now an element on the page with ID "quiz-metadata-element"
> Details are:

```
<div
  id="quiz-metadata-element"
  data-meta-location="review"
  data-meta-input-mode="manual"
  data-meta-question-mode="cloze"
  data-meta-answers-array="['だ','です']"
  aria-hidden="true"
></div>
```

> where:

```
data-meta-location: "review" | "learn"
data-meta-input-mode: "manual" | "flashcard";
data-meta-question-mode: "cloze" | "translate";
data-meta-answers-array: string; // A JSON stringified array of strings of either Japanese or English (depending on input language)
```

> Please note that the anser language can change and there can be multiple items in the array.