replace in-house solutions for randomization with faker.js

[meszaros-lajos-gyorgy]

For example pickWeightedRandoms can be substituted with:

faker.helpers.weightedArrayElement([{ weight: 5, value: 'sunny' }, { weight: 4, value: 'rainy' }, { weight: 1, value: 'snowy' }]) // 'sunny', 50% of the time, 'rainy' 40% of the time, 'snowy' 10% of the time

https://fakerjs.dev/api/helpers.html

Needs to be checked if faker.js supports seedrandom or whether it has it's own solution for seeding.