Extract snippet preprocessor

[rr404]

(Needs rebase on main rather than stack health)

Allows to copy the content of elements with data-extract attribute into elements with data-extract-copy attribute matching <page_id>:<data-extract_key>

example in this PR:

• Copied snippet of Troubleshooting page
• From this extract marked container
• To this placeHolderDiv

How it works:
in page id console_issues:

<div data-extract="stackhealth_issues_list">

Some text
</div>

in any other page

[aws-amplify-eu-west-1]

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