FR: Allow search name and search content together

[SBGit-2019]

The simple search dialogue can be switched to search names or content of documents. It would be useful to have a third option to do both. So execute both queries and combine results.
Use case is for small documents where a keyword is only in the title. Then you need to try both searches to find it. Would be good to do it in one go.

[eikek]

As mentioned in #2617 I'd rather go away from all these options, leaving one default for the case you didn't use a field:value pattern.