Overhaul sketch UI

[dabreegster]

This is a large change to the sketch UI. Demo at https://acteng.github.io/atip/move_draw_controls/scheme.html?authority=TA_North+Lincolnshire

• the top toolbar remains visible in all modes
• each mode's draw controls appear in a second row of the toolbar
• the distinction between creating/editing geometry and a form goes away. While drawing something new, you can immediately fill out the form. After clicking an object to edit, you can edit both geometry and the form at the same time
• for 3 tools (split route, streetview, georeference image), the left sidebar remains in the neutral list mode

TODOs that must be done before merging:

• Fix margins in the toolbar
• Adjust the position of the geocoder widget; it overlaps right now
• Fix the help icon; it leaks out of the box and jumps around because of its hover margin
• Generally make sure the toolbar matches Figma and appears reasonably on small screens
• Decide where the Delete button should go
• Possibly have a second copy of the main buttons in the left sidebar, floating/sticky at the top or bottom
• Handle the huge route waypoint geocoder list

Some steps I'll save for a separate followup:

• Use a marker for point mode, so editing an existing point is more normal
• Merge the freehand / snapped polygon tools

[dabreegster]

The bizarre wrapping behavior of checkboxes and radio buttons wasn't a flex problem. max-width is set by govuk components a certain way that our usage broken. This appears to work fine on both small and large screens:

[dabreegster]

I've fixed almost all of the margin/styling issues, after understanding the root causes with enough time in Firefox inspector. (Checkboxes and radios had max-width that was interacting oddly with our setup.) I've tested all of the tools both for creating something new and editing, and everything looks/feels correct to me. So I'm going to merge this in, update the other repo, and continue on with smaller tasks listed in acteng/atip#536