Run both the baseline and the simulation with interventions and plot the baseline in grey line.

[jryu01]

Description

• When there's intervention policy, run both the baseline and the simulation with interventions and plot the baseline in grey line.
• Baseline simulation is plotted on the chart when there's single variable is selected for the chart, It doesn't display the baseline if multiple variables are selected for the chart.
• Refactored to use client event instead of poller to check the simulation status (since we are already doing the polling in the backend and notify using the client event)

Resolves #5054