preview - don't set options as a const to avoid conflict with Global Scope

[cderv]

fixes #12513

Currently quarto preview script will define const that is available in Global scope in the previewed HTML

quarto-cli/src/resources/preview/quarto-preview.html

Lines 6 to 14 in 73805d3

	const options = {
	origin: "<%- origin %>",
	search: "<%- search %>",
	inputFile: "<%- inputFile %>",
	isPresentation: <%= isPresentation %>
	}
	document.addEventListener("DOMContentLoaded", function () {
	window.QuartoPreview.init(options);
	});

Here is an example of the options being seen in JS

---
title: "my board"
format: html
engine: knitr
---

# content

```{js}
//| echo: false
document.addEventListener("DOMContentLoaded", function() {
  const pElement = document.createElement("p");
  const codeElement = document.createElement("code")
  codeElement.textContent = JSON.stringify(options);
  pElement.appendChild(codeElement)
  document.querySelector("#content").appendChild(pElement);
})
```

It does not seem like a good thing that is defined globally and impact any JS script.

This PR is here as a draft to discuss this idea.

I don't know if some other tools can rely on these generic options being available. Hopefully not because it could be redefined too. If this should be made available, it should probably be namespaced.

---
title: "my board"
format: html
engine: knitr
---

# content

```{js}
//| echo: false
document.addEventListener("DOMContentLoaded", function() {
  const options = "{new: 'hello'}"
  const pElement = document.createElement("p");
  const codeElement = document.createElement("code")
  codeElement.textContent = JSON.stringify(options);
  pElement.appendChild(codeElement)
  document.querySelector("#content").appendChild(pElement);
})
```

[cderv]

I added a way to get the preview options if needed

---
title: "my board"
format: html
engine: knitr
---

# content

```{js}
//| echo: false
document.addEventListener("quarto-preview-initialized", function(e) {
  const pElement = document.createElement("p");
  const codeElement = document.createElement("code")
  codeElement.textContent = JSON.stringify(e.detail);
  pElement.appendChild(codeElement)
  document.querySelector("#content").appendChild(pElement);
})
```

[cscheid]

Yeah, this is fine. (Essentially no one should be writing to the global scope, libraries or us.)