Refactor `ProductMedia` forms on product editing
Refactor `ProductMedia` forms on product editing

Rename `ProductMediaForm` to `BaseProductMediaForm`
Move thumbnail creation to `BaseProductMediaForm`
Add `ProductMediaForm` for other medias than images

Refs SHOOP-1045

suutari/shoop,lawzou/shoop,lawzou/shoop,shoopio/shoop,suutari/shoop,akx/shoop,suutari/shoop,jorge-marques/shoop,shoopio/shoop,lawzou/shoop,hrayr-artunyan/shuup,suutari-ai/shoop,suutari-ai/shoop,taedori81/shoop,shawnadelic/shuup,akx/shoop,taedori81/shoop,jorge-marques/shoop,shawnadelic/shuup,hrayr-artunyan/shuup,hrayr-artunyan/shuup,jorge-marques/shoop,akx/shoop,shoopio/shoop,suutari-ai/shoop,shawnadelic/shuup,taedori81/shoop