Steam SteamDB Button

Adds a link to https://steamdb.info/ page of given link to game pages on Steam store.

NOTE: if there is more than one buy button (game that has multiple versions, free demo, DLCs, OST, bundle, etc.) there is a button added near each, but they all lead to same page, the URL of history page is based on URL of the game and nothing else.

NOTE: compatible with my other script - https://greasyfork.org/en/scripts/452120-steam-price-history-button