Migrate line chart vis type to Vega-Lite rendering

[joshuarrrr]

In the vis_type_vislib plugin, add the ability to render a line chart via the Vega-Lite render expression renderer instead of the d3 implementation within vis_type_vislib. The goal is complete parity with existing vislib line chart options, interactions, and visual look/feel.

• Create mapping function that can generate the appropriate vega-lite spec given a visConfig
• Allow conditional rendering via either expression to aid testing and rollout.
• Minimal migration of Visualization line charts to vega-lite #2915

[joshuarrrr]

@lezzago - This issue may be overly broad compared to what you're actually planning to tackle. Feel free to create more specific sub-tasks as issues and re-assign to those as needed. I just wanted to track that you're actively working on this.