`hasRenderedText` (markdown etc)

```js
export const isRenderedTextFile = isSingleFile && endsWith(md)
export const hasRenderedText = isRepoRoot || isRenderedTextFile || etc
```

These shouldn't include SVG and other rendered content

Partially implemented in https://github.com/refined-github/refined-github/pull/4151/files#diff-a1b04b00ad1bdc63f8898dfbf43b2faf61ae3be4f50182d5a144d3e7f0dc7c29R14