Implement all Figma designs

[dabreegster]

I'll use this bug to track discrepancy between UI designs in Figma and reality. Was trying https://github.com/dabreegster/abstreet/projects/7 for a while, but issues are easier to maintain.

• [x] Click individual intersections in the multi signal sidepanel to jump to that intersection
• [x] New traffic signal editor: crosswalks
• [x] New traffic signal editor: tune arrow style
• [x] Cancel out of traffic signal editor (go straight back to simulation?)
• [x] Fix inactive button height (file save)
• [x] The great button overhaul
• [x] File save dialog (don't allow overwriting)
• [ ] Bulk edit results (show errors)
• [x] Bulk edit lanes needs an adder/remover for lane type transformations
• [ ] Edit mode loader in the main sandbox screen, near "traffic"
• [x] More detailed agent meter tooltips
• [ ] Minimap filters
• [x] Agent intention bubbles (need to plumb trip purpose for some of them)
• [ ] Align zoom in/out controller with pedestrian minimap checkbox
• [ ] New trip table
• [x] Access signal demand dashboard from intersection info panels and also map overlays
• [x] Use ▼ or SVG for dropdowns again
• [ ] Throughput line plot changes
• [ ] Audit/update language everywhere: "vehicles" and "commuters". Details on notion.
• [x] Audit/update numeric precision -- times and durations and most things can be rounded to whole numbers
• [x] Don't clip tooltips to scrollable panels
• [ ] New agent info panels
• [ ] New trip summaries

And a few more from #551:

• [ ] Allow the layers panel to be minimized. Always open a new one full; don't be sticky.
• [ ] Enable the info panel and layer panel to be draggable.
• [ ] Blur beneath the panels instead of increasing opacity so much
• [ ] Launch Santa and the 15m tool from the main menu of A/B Street, even though they're now separate apps
• [ ] Manually minimize the minimap when zoomed in. This decision is sticky.

[michaelkirk]

I can start with these ones:

• [x] Don't clip tooltips to scrollable panels
• [x] Use ▼ or SVG for dropdowns again: https://github.com/dabreegster/abstreet/pull/344
• [x] Agent intention bubbles (need to plumb trip purpose for some of them)

[dabreegster]

SGTM! I forgot to check off tooltip clipping this morning; 6f1ffe66b56f9f470069c986c08f234e1994dc5a should fix that