Do not open setting tab on extension update events

[pravj]

Context
As per the current implementation (check the background script), the settings tab is opened on every onInstalled event.

Problem
It results in behavior where the tab is opened on every extension version update as well as the first installation event, which is unnecessary.

Solution
The enhanced implementation can validate using the local-storage if the extension is set up (user-access-token) or not. If the extension is activated, it can ignore the onInstalled event.

[jerone]

[..] where the tab is opened on every extension version update as well as the first installation event [..]

And for some reason, also opened on every Firefox update.

Every time I see the settings page, I think something is wrong with the configuration of this extension.