Add hash params in competitions overview page

[maxidragon]

After migrating the competition overview page to React, it is not possible to copy a link with some filters enabled. I think adding at least region as hash param will be great

[kr-matthews]

For whoever ends up doing this, the incidents log had the analogous issue when migrating to react, so for consistency it would be best to check how it was done there and do it the same way here.