A way to provide histogram y-domain directly

[harold]

https://github.com/techascent/tech.viz/blob/5f0ae9d671648bcafb0fa7fa730b610610c68748/src/tech/viz/vega.cljc#L214

This line can be changed to something like: :domain [0 50] which can be useful in cases where one is comparing histograms directly (to ensure they have the same scale)... Add something here so that this can be provided from the outside optionally.