feat: replace chb with consent groups and preserve runtime config (api#317, #17)

tests/check-utm-redirect-contract.php

@@ -37,7 +37,7 @@ $expected = [
     'degr' => '1',
     'registration' => 'after',
     'bchoice' => 'a',
-    'chb' => 'b',
+    'cons' => '2',
     'tp' => $config['utm']['tp']['default'] ?? null,
     'focus' => 'face',
     'utm_source' => 'stage-ad',