WIP: Re-enable ability to change sorting in search result lists

Currently, it's not possible to change sorting in search results from the default "search relevance".

When searching for a file users sometimes have problems with locating it in long lists of search results, and have no way of improving this situation manually.

To fix that, re-enable sorting in search result lists via the view menu options.

This merge request is a draft implementation of #374 (comment 726650) and does the following:

• shows sorting options in view menu for list view like they are currently available for the grid view
• adds "search relevance" to sorting option in the view menu that shows only in search, just like the "last trashed" is available only in trash
• re-enables ability to change sorting options in search by showing the sorting options in view menu for both list and grid views

Screenshot:

Fixes: #374 (closed)