Add bounty timer to isolation vaults

[(XBOX)KayAitch]

When you start a vault mission you have until the next Vome/Fass transition to do all three, and at the moment if that timer runs out the current vault bugs out and is just empty.

Even if the bugs are fixed the hidden timer is kind of a pain.

Like other time-limited bounties there should be a counting down timer to the next Vome/Fass change always on screen (top left, same as for any other bounty) so that we know how much time we have left (and pub users get an idea that there may be limited time without lengthy chat sessions and all the toxicity and new-player-unfriendlyness that causes).