Scheme sketch changes pre-launch

[dabreegster]

Each medium-largeish PR updating the design has a few leftover tasks, going to track them all here for simplicity.

• Check the geocoder position
• Fix bottom margin for the georeference image mode
• Decide where the Delete button should go for editing a feature
• Possibly have a second copy of the finish/cancel/delete buttons in the left sidebar, floating/sticky at the top or bottom
• Use a marker for point mode, so editing an existing point is more normal
• Merge the freehand / snapped polygon tools
• Overhaul the route snapper tool using markers
• Show snappable nodes (if perf problems can be overcome)
• Clean up the govuk-svelte components a bit; leftLabel and noBottomMargin may not be the right approach after all
• Rewrite the About popup for SS
• Write an About popup for SB
• Check names of all pages (including HTML titles), and scrub out "ATIP" generally
• X button style (everywhere)
• Use on-map controls for line measurement, streetview, basemap (all tools)
• Preserve list mode position
• Reset edit form position
• Adjust wording for managing "your" local sketches
• Find smallest authority for SB -> SS for main schemes? (Revisit why this is necessary)
• Refresh authority boundaries