Prefix inline anchor ids with `user-content-`

What does this MR do?

Prefix inline anchor ids with user-content- to avoid conflicts and update the sanitization filter to allow prefixed ids.

The cross reference (i.e. a link to another location within the current AsciiDoc document) with the text "use cross references" will now correctly navigate to the corresponding location.

Learn how to xref:cross-references[use cross references].

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[[cross-references]]A link to another location within an AsciiDoc document or between AsciiDoc documents is called a cross reference (also referred to as an xref).

resolves #196071

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Does this MR meet the acceptance criteria?

Conformity

• Changelog entry
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