Add seedrandom.js library to Lab

[#62264458]

Actually there is no github repo for this tiny library, so it's
just copied into vendor dir.
Add seedrandom.js library license information

[#62264458]
Use seedrandom.js lib and set explicit seed for Math.random()

[#62264458]

Of course this solution is pretty naive.
What if user reloads a model a few times?
What if he uses a tick history and then plays the simulation again?
Such scenarios will break predictable simulations, so we should
carefully consider where and when the seed should be set.