[FEATURE] Support scripted fields in index pattern for CSV

[joshuali925]

Is your feature request related to a problem?
since reporting directly searches the index with the DSL query in saved search, it does not know about the script field stored in index pattern. scripted fields won't show up in csv reports

What solution would you like?
support scripted fields by combining scripted fields in index pattern with DSL query

What alternatives have you considered?
A clear and concise description of any alternative solutions or features you've considered.

Do you have any additional context?
Add any other context or screenshots about the feature request here.

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