Support per-burst BurstDelays

[reaperrr]

Original TS engine 2.x (2.x patch, Firestorm) added support for BurstDelay0-4, allowing to define individual delays for bursts 2-6.

In our case, I'd turn int BurstDelay into int[] BurstDelays. For individual delays modders will have to define the whole list of delays (i.e. if Burst: 6 where delay between 2nd and 3rd and 4th & 5th should be 10 and 5 between all other bursts, it would have to be BurstDelays: 5, 10, 5, 10, 5).
For convenience, if only a single value is defined it will be used for all bursts.

I have a branch for this, but it's based and therefore depends on #13597.

Needed to bring Juggernaut even closer to original (first 2 bursts almost simultaneously, 3rd with some more delay).