Related issue: https://github.com/quarto-dev/quarto-cli/issues/90

Thanks for all the fabulous work.

Would be possible to allow users to place the subfigure caption indicator at the top left corner of the image and keep the figure caption at the bottom?

For example,

```
---
fig-sub-cap-location: top
fig-sub-cap-merge: true
---

::: {#fig-elephants layout-ncol="2"}
![Surus](elephant.png){#fig-surus}

![Hanno](elephant.png){#fig-hanno}

Famous Elephants
:::
```

would give

![Screenshot from 2022-05-06 13-25-04](https://user-images.githubusercontent.com/1506457/167072208-69622eb5-3051-49df-9d75-58b22f98393e.png)

2022-05-06T05:27:20Z
rgaiacs
Future
open
Subfigure caption indicator at the top left corner
https://github.com/quarto-dev/quarto-cli/issues/811