feat: Groups (Map-Mode): Frontend

[resah]

This is part of the feature "Groups":
To visualize teams, or as we call it at AOE "circles", it should be possible to define groups. To accommodate for different use cases, there are two different variants for grouping. This feature is part of "Map groups (area)":
Draw an area in a specific location (map), which is assign a name (and maybe other properties).
Use cases: team areas, event spaces, children area, ...

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Frontend

• New section in left navigation bar Groups
• List all groups
• select group to display in map and show popup (with name and description)
• + icon to draw new area in map and assign properties (see backend part)
• Edit icon to redraw in map and update group properties
• trash icon to delete group

Maybe relevant

• https://github.com/bopen/leaflet-area-selection
• https://github.com/sandropibia/Leaflet.SelectAreaFeature/
• https://svelte-select-examples.vercel.app/examples/advanced/create-item