Fix bug: Calendar view does not open in some cases.

[IsaDavRod]

From Sam in Discord:

Right now we only ever have one calendar tab open at a time, and if it's opened again we attempt to focus that tab. Unfortunately, there are edge/corner cases that prevent the calendar from being focused but still identified as existing, so clicking the calendar button doesn't work. We've been throwing bandaids on it but nothing has worked perfectly; we still have complaints about it not opening sometimes.

Solution: If the user clicks on the Calendar button two times within a short window, then force open calendar view in a new tab. Also add a settings toggle to Always open new Calendar Tab instead of trying to Focus an existing Calendar Tab