Add source links when using sphinx.ext.viewcode

[Eric-Arellano]

Implements #454 for projects that are using sphinx.ext.viewcode. All 3 of our projects were historically using it until I turned it off after removing qiskit.org, so the historical API docs are good to go. I'll restore it for current versions of these projects and regenerate the docs.

This implementation is not a perfect implementation:

1. The visual design is a little awkward, especially the lack of padding. This can be improved via Design GitHub source code links #518

2. The link only takes you to the overall code page, not the specific lines. This could be improved via Switch Qiskit, Runtime, and Provider to have more precise source code links #517.

But it's good enough to not block on these improvements.

This PR regenerates all Runtime historical versions, but not any current versions nor Qiskit historical versions.

How source code URLs are determined

sphinx.ext.viewcode embeds a copy of every Python file used in API docs and uses internal relative links like ../modules/qiskit_ibm_runtime/ibm_backend.html. They correspond to Python files we can be confident exist. We transform those relative links into GitHub links here:

documentation/scripts/lib/api/processHtml.ts

Lines 94 to 105 in 790e937

	export function removeHtmlExtensionsInRelativeLinks(
	$: CheerioAPI,
	$main: Cheerio<any>,
	): void {
	$main.find("a").each((_, link) => {
	const $link = $(link);
	const href = $link.attr("href");
	if (href && !href.startsWith("http")) {
	$link.attr("href", href.replaceAll(".html", ""));
	}
	});
	}

documentation/scripts/lib/api/processHtml.ts

Lines 163 to 183 in 790e937

	export function replaceSourceLinksWithGitHub(
	$: CheerioAPI,
	$main: Cheerio<any>,
	baseSourceUrl: string,
	): void {
	$main.find("a").each((_, a) => {
	const $a = $(a);
	const href = $a.attr("href");
	if (
	href === undefined ||
	href.startsWith("http:") ||
	!href.includes("_modules/")
	) {
	return;
	}
	//_modules/qiskit_ibm_runtime/ibm_backend
	const match = href.match(/_modules\/(.*?)(#|$)/)!;
	const newHref = `${baseSourceUrl}${match[1]}.py`;
	$a.attr("href", newHref);
	});
	}

Our links assume that there is a branch called stable/<versionWithoutPatch in GitHub, like stable/0.8.

Replacing [source] with GitHub ↗︎

We remove the original link from Sphinx and replace it with our own. This is important so that the link is not included in the <code> HTML element incorrectly. It also allows us to set a custom link label and title (the text when highlighting).

[arnaucasau]

Looks good to me, thank you Eric! Tested locally and all works well!

[Eric-Arellano]

"Extended checks" fails but not due to anything from this PR. It was already broken. I'll fix in a follow up.