Set embedded app theme to match the site theme

[sfc-gh-dmatthews]

📚 Context

This PR passed the currently selected theme to all Community Cloud embedded apps as a query parameter to make them match the site theme.

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[sfc-gh-tteixeira]

Approved after comments addressed

[sfc-gh-tteixeira]

Why is the function needed?

[sfc-gh-tteixeira]

If currentTheme isn't used anywhere else, I think it's cleaner to just instantiate it to "dark_theme" or "light_theme" directly, rather than do a more brittle string interpolation later on.

[sfc-gh-tteixeira]

Actually, just instantiate to embed_options=dark_theme directly, and avoid a second string interpolation below.

Same for light.

[sfc-gh-tteixeira]

It's cleaner to add the theme directly in the embedQueryParams array, and let the string joining logic above handle it.

That is, remove the if (query) { block but keep the code inside, modified like this:

    const embedQueryParams = [themeParam];
    const normalQueryParams = [];

    if (query) {
      query.split("&").forEach((qStr) => {
        if (qStr.startsWith("embed=") || qStr.startsWith("embed_options=")) {
          embedQueryParams.push(qStr);
        } else {
          normalQueryParams.push(qStr);
        }
      });
    }

    embedQueryStr = "&" + embedQueryParams.join("&");
    normalQueryStr = "&" + normalQueryParams.join("&");

[sfc-gh-dmatthews]

I think I followed your suggestions. I couldn't get rid of the function entirely, because server-side rendering broke. So, re-requested a review to make sure it satisfies you requests.