[Feature Request] Add support for matched_fields with the unified highlighter

[nomoa]

Is your feature request related to a problem? Please describe

matched_fields is currently only supported with the fvh highlighter.
The fvh highlighter is generally cumbersome to use since it requires term vectors to be stored.
matched_fields is generally useful when a field is analyzed differently with the help of dedicated sub fields. In order to blend the matches from all these fields into a single snippet matched_fields is the solution.

Describe the solution you'd like

In lucene 10 a new function withMaskedFieldsFunc was introduced to let the unified highligher discover what subfields might contains additional matches. It should be relatively straightforward to adapt the current implementation to pass matched_fields to this function.

Related component

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Describe alternatives you've considered

No response

Additional context

No response