Fix expand/collapse all on site, make highlightjs lazier

[Alexendoo]

This fixes the buttons that expand/collapse all the lints in the list, it also makes code block syntax highlighting only happen when the specific lint enters the viewport since highlighting them all at once was fairly heavy

There's also a few miscellaneous inline event handler removals

script.js and highlightjs are now loaded with defer so that the download can start earlier

Also fixes #14048, we were calling highlight on the pre in <pre><code>...</code></pre> but highlightjs wants us to call it on the code element

changelog: none

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