Open game store page in webview and refactor

[arielj]

This PR fixes #863 by making the stores open in the webview instead of a popup.

I did a small refactor:

• moved the epic url generation at the loading of the file so gameInfo.store_url works for both gog and epic
• we can open the generic page with no language code and the epic store will use the user's language
• I cleaned a little bit of the webview url handling for the login/:runner routes

---

Use the following Checklist if you have changed something on the Backend or Frontend:

• Tested the feature and it's working on a current and clean install.
• Tested the main App features and they are still working on a current and clean install. (Login, Install, Play, Uninstall, Move games, etc.)
• Created / Updated Tests (If necessary)
• Created / Updated documentation (If necessary)

[flavioislima]

Looks good.
One thing I noticed though is that it doesn't highlight the right store when opening it.
So for epic games, the epic games submenu should be marked as active. Should be a simple fix I believe.

[arielj]

@flavioislima this is ready for a second review, I added the highlight on the sidebar links when it applies

[flavioislima]

Pretty good! Thanks for that! 👍🏽