Chart: Fix bug when utilizing "step-after" type of chart

[diehbria]

This task is to enable a user to configure their chart to display as a "step-after" chart (A type supported by echarts, the charting library utilized by IoT App Kit).

Currently, when a user adds a chart and selects the type as "step after", it displays the chart as the wrong type, and does not show as a "step-after" chart.

The "type" configuration for a chart is found by selected a line/scatter chart, and then going to the "styles" section of the right side configuration pane, where you will find a drop down such as shown below:

More information about echarts stepcharts can be found at https://apache.github.io/echarts-handbook/en/how-to/chart-types/line/step-line/

Tasks

Beta Give feedback

1. A user is able to select step-after and have their chart correctly display as a step-after line chart.