Add a filter hook to the "Insert/edit link > link to existing content" query

[lumpysimon]

There's currently no way to filter the results of the query performed when using the "Insert/edit link > Link to existing content" option in the modal window.

In my case, I need to restrict the post types shown in the results based on the user's role. You might also want to change the order/orderby parameters, etc.

[SergeyBiryukov]

Duplicate of #18042.