get rid of hideSearchBar option by using existing capability

[butonic]

Currently web checks a dedicated option to disable the search bar, introduced wcith #3817

However, the capabilities do contain the list of reports that clients can fire against webdav.

For backend search (aka sdk search) the capabilities.dav.reports string array has to contain "search-files":

...
{
  "dav":{
    "chunking":"",
    "trashbin":"1.0",
    "reports": ["search-files"],
    "chunkingParallelUploadDisabled":false
  }
}
...

Web should rely on that dav.reports property in the capabilities instead of an option in the config.

Another report is a filter-files report which is used to filter files by favorites and tags ... but that is a different issue.

[kulmann]

Agreed, capability should have precedence and the config.json option can be dropped immediately.