Insights: Prepare API handlers on the frontend for the search result insight preview

Created by: vovakulikov

Part of (preparation for) https://github.com/sourcegraph/sourcegraph/issues/38430

Background

The original issue implies that we're going to have code insight live preview on the search page. In this issue we should prepare a data resolver on the search result page. We can't use code insight live preview handler on the search result page since this is completely enterprise functionality and we have technical difficulties to put Enterprise parts into OSS pages.

Note that chart (visualization part) will be connected to this data resolvers in a separate issue later.