Show indicator when an opened tab is snoozed for later

[waldyrious]

If I snooze tab foobar.com to sometime in the future, and later I manually open the foobar.com website, I would like the SnoozeTabs extension icon to show an indicator/badge to signal that the tab is already scheduled for later and can be safely closed.

The same information could be included in the context menu: in the "Snooze tab until..." options, the first one could be the actual date that the tab is currently snoozed to.

Even better — it should be possible to modify the snooze date if I click the extension's icon or the context menu on a tab that's already snoozed.

[waldyrious]

For reference, this is the current behavior of the Time Capsule extension (which uses a very similar system to this one).