Query backtrace results custom limite option

[erikn69]

Closes #1186

Usage:

// `true` get 5 as default
'backtrace'         => 2,      // Use a backtrace to find the origin of the query in your files.

laravel-debugbar/config/debugbar.php

Line 212 in 9506950

'backtrace' => true, // Use a backtrace to find the origin of the query in your files.

laravel-debugbar/src/DataCollector/QueryCollector.php

Line 304 in 9506950

return array_slice(array_filter($sources), 0, 5);