data_limits should respect the plot's transformation

[asinghvi17]

Right now, if I translate a plot, that doesn't reflect in data_limits.

Ideally, my sense is that it would reflect there.

[ffreyer]

I think data_limits and boundingbox also need to be defined more clearly.

I'd say data_limits should probably just look at plot.converted and ignore the extent or markers, scattered meshes, heatmaps, etc. boundingbox should include that stuff. It would probably also be useful to have boundingboxes that returns a boundingbox per element. (Or a boundingbox(plot, index)?)

When it comes to applying transformation I think the untouched version should probably just look at the raw data. I.e. the bounding box/limits should match up if you apply all the same transformations. Though for usability I think we should just have target_space as an argument in these functions.

[SimonDanisch]

Closed in favor of #2881