Fix visualization of OQ-Engine outputs needed for risk workshops

[ptormene]

• For Asset Risk Distributions, show also a table of consequences if they are available (fixes Unable to display Aggregated Loss Distributions on scenario_damage calculation with consequence models  #808)
• Fix visualization of aggcurves and aggcurves-stats (fixes Aggregate Risk Curves unable to present loss exceedance curves #809)
• Disable Load layer and Aggregate buttons for avg_losses-rlzs in case avg_losses-stats is present (because the engine, in case stats are available, does not extract rlzs)
• Add Load table button for damages-stats and aggrisk-stats (it was easy to add them though not requested)
• Warn the user (and ask for confirmation) in case the 'Load csv as table' dialog would load a csv bigger than 10 MB (some OQ-engine outputs can be very big)
• Fix list of selected tags reported in the commented header of the csv exported by the Data Viewer

Companion of some engine-side changes:

• Add consequences to composite risk model attrs; include consequences when doing extract_agg_damages oq-engine#8394
• Making it possible to extract the individual loss curves per tag combination oq-engine#8390
• Fix realization repr (stray quote) oq-engine#8397