When you open a new tab while the search mode is enabled, the
newly opened tab also starts the same search (Because new tab is opened with
the current view url), but the search box is in read-only mode. So you cannot
close the search bar nor edit the search text.

This patch fixes this by parsing the search url. The value of the "search"
parameter is used as search text and the value of the "url" parameter is used
for the search path ("root" folder for the search when "Search from here" mode
is enabled).

In case of Baloo search urls, we use Baloo::Query::fromSearchUrl.

Removed everything related to read only mode in DolphinSearchBox, not needed
anymore.

REVIEW: 111968

FIXED-IN: 4.13.0