Productivity Analytics - Add metric chart to storybook

Background

While discussing some options for improvements to some existing charts, it was noticed that the current charts for groupoptimize arent very straightforward to experiment and interact with.

Related to &11681

Proposal

• Add a story file for the metric_chart
• Add a story file for the mr_table

Implementation guide

• Add a new story file named metric_chart.stories.js for the metric_chart.vue component
  • The default story should render the chart with data
  • Add a story for the chart without any data available
  • Add a story for the chart in the loading state (isLoading=true)
• Add a new story file named mr_table.stories.js for the mr_table.vue component with all props specified

Take a look at the type_of_work_charts.stories.js file for some inspiration