Feature: scenario compare between multiple scenarios

[victorterpstra]

Allow a user to select multiple scenarios for a multi-scenario compare view. Load data from all these scenarios Custom visualization pages can then create plots over multiple scenarios.

Technical suggestions:

• Load the multiple scenarios in single table, i.e. keep the scenario_name in the DataFrame
• Will make it easier to generate plots where the scenario_name is one of the visualization properties (like in the DO Experiment)

[victorterpstra]

Notes:

1. End goal:

   • a PlotlyManager with properties sceanrio_compare_inputs, scenario_compare_outputs
   • Inputs include the Scenario table (only for the selected scenarios)
   • All DataFrames contains primary key scenario_name
   • The 'create_plotly_fig' method typicaly creates a dedicated scenario-compare figure
   • So, like the DO Experiment, we get dedicated scenario compare charts / pages
   • (Although the plotly method could automatically switch between views)

2. Select scenarios to compare:

   • Include the current scenario
   • Include any 'reference scenario'
   • Include selected scenarios

3. DB query and caching

   • New cached db query procedure (in addition to to current cached procedure for single scenario)
   • Use caching based on set of scenario-names.

4. Dashboard VisualizationPage configuration

   • Keep same set of input/output tables specification
   • Include a load_scenario_compare_data flag: if True, loads the scenario-compare inputs/outputs (This avoids loading scenario-compare data for pages that do not use/support scenario-compare)

5. ScenarioDbManager APIs:

   • Query DB table for scenario_name IN list of scenario-names. (I.e. do not query table multiple times per scenario)
   • def read_multi_scenario_tables_from_db(self, scenario_names: List[str], input_table_names: Optional[List[str]] = None, output_table_names: Optional[List[str]] = None) -> (Inputs, Outputs):