[FEAT]: Comparison charts for TA3 operators

[pascaleproulx]

We currently support looking at simulation output one model variables per chart. It works fine except when a model is stratified, the user need to compare the strata members so this feature would support that.

• There should be an additional section in the output settings of the ta3 operators called 'comparison charts'.
• The multi-select UI widget should support typing to filter the variables list in the dropdown and bulk select all the variables left after filtering. E.g. type 'I_' should filter the list to just the model variables related to the infected states e.g. I_young, I_middle, etc.
• Implement rules such as:
  a) if there are 5 or less variables selected, create one chart with one line per variable, each in a different colour (with legend)
  b) if there are 6 or more variables selected, create a panel of small multiples (one thumbnail chart per variable), all with the same y axis
• When the user clicks on the gear icon for the new chart, they can then change the default from the rule above (e.g. switch between 'All in one chart' and 'Small multiples', and if 'Small multiples' is selected, opt for unlocking the y axis or show before (grey lines) too.