Convert Issue Analytics chart into ECharts

What does this MR do?

It removes chart.js dependency and leverages echarts based column chart from gitlab-ui to display issue analytics chart.

Questions & issues

• Chart's popover form gitlab-ui is not configurable. There is no way to pass the template for rendering tooltip, so current implementation doesn't have correct tooltip (with issues created label) in comparison with a previous version. Should we create a separate issue for this fix in gilab-ui?
• Should we display zero values?
• Tooltip is shown outside the column. Should we create a separate issue for this fix in gilab-ui?

Issue Ref: #12593 (closed)