Fix Plotly require.js config mechanism

[jkrumbiegel]

Quarto expects the preamble for a Plotly plot using require.js to exist in a cell only once. So we keep track whether a PlotlyBase plot has already been displayed, and only if not, we expand the plot into two cells, the preamble and the plot's html.

The fix on the quarto side is not in a prerelease, yet, but locally I confirmed that this works with latest master:

---
engine: julia
keep-md: true
---

```{julia}
using PlotlyJS

plot(rand(10,4))
```

and another plot

```{julia}
plot(cumsum(randn(100)))
```

[codecov]

Codecov Report

Attention: Patch coverage is 0% with 20 lines in your changes missing coverage. Please review.

Files	Patch %	Lines
...ookWorker/ext/QuartoNotebookWorkerPlotlyBaseExt.jl	0.00%	19 Missing ⚠️
...ebookWorker/ext/QuartoNotebookWorkerPlotlyJSExt.jl	0.00%	1 Missing ⚠️

📢 Thoughts on this report? Let us know!