Search result web UI plugins should not be constrained to Advanced Options

[Enet4]

Web UI plugins of slot type result-option install custom content inside the Advanced Options column. If we want to extend the search results with content that is always visible in each row, it is currently not possible.

Ideally, we would want to be able to indicate through meta-data whether the result option plugin is to be installed as an advanced option (default) or in an always-visible column. In the latter case, a new column would appear for non-advanced options if any of such plugins are set up in Dicoogle.