Extend functionality of stacked bar charts to display series labels above the bar

[charlesons]

Extend functionality of stacked bar charts to display series labels above the bar, so that following chart can be created:

Above chart is part of https://climate-change.data.gov.uk/articles/emissions-embedded-in-trade-and-impacts-on-climate-change

[charlesons]

Looked into the Plotly API to see if there are options for showing both the x and y axes horizontally and it seems this is not possible.

Plotly does support showing different Y axes on the same chart where data series cover different sized domains but this isn't the same thing that we want to achieve.

Some alternative ways we can get the desired results are:

1. Use the existing chart builder capability and show the EU / Non EU labels in the legend (something similar to below)

2. Use a static image

3. Create a simple custom data vis (much as we have done with the horizontal bar data vis on the dashboard tiles).

4. Introduce the ability to annotate charts and then annotate the EU / Non EU labels onto the chart

[charlesons]

Climate Change team stated their preference is option 3 initially but that the option to annotate charts would also be useful in the future.

The next step is to look into the feasibility and work effort for implementing option 3 as it would be outside the current framework of using Plotly to render the data vis in Chart Builder.

Moving the ticket back to sprint backlog until other issues in progress are completed.

[peterfrenchons]

Not necessary for initial go-live

[edd-harvey]

No longer required