Support `-scap` in Float crossrefs consistently across formats and input options

Bug description

Minor issues with the fig-scap: when there are multiple subfigures. When using subfigures and subcaptions, the fig-scap is no longer used in the list of figures, instead the full caption is used and the scap is ignored.

---
title: "scratch"
toc: true
format: 
  pdf:
    table-of-contents: true
    lof: true
---

```{r}
#| fig-cap: "Long caption 1."
#| fig-scap: "Short1"
#| echo: false
plot(mtcars)
```

```{r}
#| layout-ncol: 2
#| label: fig-charts
#| echo: false
#| fig-cap: "Overall longer caption."
#| fig-scap: "Short2"
#| fig-subcap: 
#|   - "Long caption 2."
#|   - "Long caption 3."
plot(mtcars)
plot(cars)
```

Related to this as well is the potential for using scap in divs for markdown figures, ![](). Not necessarily a bug as I'm unsure if scap is supported for HTML output.

RStudio Build 576. MacOS 12.6, Intel Macbook Pro 15-inch (2017).

Checklist

• Please include a minimal, fully reproducible example in a single .qmd file? Please provide the whole file rather than the snippet you believe is causing the issue.
• Please format your issue so it is easier for us to read the bug report.
• Please document the RStudio IDE version you're running (if applicable), by providing the value displayed in the "About RStudio" main menu dialog?
• Please document the operating system you're running. If on Linux, please provide the specific distribution.