Mobfox Adapter: gpp support (prebid#4887)

* initial

* Update mobfoxpb.md

* Update mobfoxpb.md

* Update mobfoxpb.md

* Update mobfoxpb.md

Add `key` parameter

* updates for prebid v5

* update enable_download

* update params

* additional info

* update info

* lint

* gpp support

---------

Co-authored-by: Aiholkin <artem.iholkin@smartyads.com>
Co-authored-by: kostiantyn.k <kostiantyn.k@smartyads.com>

Author: 3 people

dev-docs/bidders/mobfoxpb.md

@@ -10,6 +10,7 @@ tcfeu_supported: true
 pbjs: true
 pbs: true
 pbs_app_supported: true
+gpp_supported: true
 gvl_id: 311
 enable_download: true
 sidebarType: 1