Allow grouped tabsets to have different tab values

Currently, for grouped tabsets to work properly, the tab names need to have the exact same content.

https://github.com/quarto-dev/quarto-cli/blob/10af0a2ddcd4134a2d2bc9b3f7a20233e0f81ba3/src/resources/formats/html/tabsets/tabsets.js#L62

It would be helpful if grouped tabsets could look at an extra attribute, e.g. data-value, that determines how tabsets are linked.

For example, you might have R and Python tabs but want to vary the text in the tab:

::: {.panel-tabset group="lang"}
### Setup in R

```r
install.packages("quarto")
```

### Setup in Python

```bash
uv pip install quarto
```
:::

::: {.panel-tabset group="lang"}
### Print in R

```r
"hello, world"
```

### Print in Python

```python
print("hello, world")
```
:::

Currently, clicking any of the tabs in one tabset panel will "break" the display in another tabset. But they could be linked via data-value, e.g.

::: {.panel-tabset group="lang"}
### Setup in R {value="r"}

```r
install.packages("quarto")
```

### Setup in Python {value="py"}

```bash
uv pip install quarto
```
:::

::: {.panel-tabset group="lang"}
### Print in R {value="r"}

```r
"hello, world"
```

### Print in Python {value="py"}

```python
print("hello, world")
```
:::

(Assuming value="py" translates to data-value="py" in the DOM.)