Fitted domain should apply to stacked domains

[nickofthyme]

Describe the bug
When using a stacked series and setting the y-axis domain.fit to true, the domain is still locked to 0.

To Reproduce
Steps to reproduce the behavior:

1. Go to https://codesandbox.io/s/cool-tree-42qto?file=/src/App.tsx
2. Comment on and off the stackedAccessors line
3. Notice the stacked series forces the baseline to be 0, and the non-stacked series accurately fits the data to the dataset

Expected behaviour
Stacked data should be fittable

Screenshots

Screen.Recording.2021-03-03.at.04.41.46.PM.mp4

Version (please complete the following information):

• Elastic Charts: master

Kibana Cross Issues
elastic/kibana#93352

Checklist

• every related Kibana issue is listed under Kibana Cross Issues list
• kibana cross issue tag is associated to the issue if any kibana cross issue is present

[markov00]

I see this from a different point of view. We should allow fitting the data only for line series, nothing else.
This because: bar and area should always start at 0 baseline, no exception. Their height/area represents their value, and we should prevent truncations.

[nickofthyme]

@markov00 Ok I agree with the exception of log scales. So line can be fitted for all cases and area or bar can be fitted when the scale is set to log. What do you think?

[markov00]

Removing the zero baseline for line series is fine in all cases.
Removing the zero baseline for area and ba is always wrong. The exception we are applying to log is more an exception to improve the rendering and reading of the chart for a particular data domain. We only know that there can be a zero when we use a log scale, so we are limiting the rendering to a similar, but very small, zero-like baseline. Applying domain fit to area or bar is not a good approach IMHO

[nickofthyme]

Won't fix per discussion with team over zoom. Main takeaways from the discussion:

• Area charts should always have a zero baseline
• Stacked log area charts don't make sense
• We should disallow log scales for area and bar charts