Rework LegendHeader, Tooltips, misc chart style

frontend/src/card/lib/CardRenderer.js

frontend/src/card/lib/utils.js

frontend/src/components/Popover.jsx

frontend/src/components/Tooltip.jsx

frontend/src/components/TooltipPopover.jsx

frontend/src/components/Triggerable.jsx

frontend/src/components/dashboard/dashboard.css

frontend/src/dashboard/components/DashCard.jsx

frontend/src/dashboard/components/DashboardGrid.jsx

frontend/src/query_builder/GuiQueryEditor.jsx

frontend/src/tutorial/Tutorial.jsx

frontend/src/visualizations/AreaChart.jsx

frontend/src/visualizations/BarChart.jsx

frontend/src/visualizations/LineChart.jsx

frontend/src/visualizations/components/CardRenderer.jsx

frontend/src/visualizations/components/LegendHeader.jsx

frontend/src/visualizations/components/LineAreaBarChart.jsx