Layout customization

[mosheduminer]

• Enable resizing the various "sections" in each route,
• as well as allow drag-and-drop to rearrange the layout.
  (a section would be, for example, (in the resource route) the bar showing database/resource names, the history timeline, the resource view. (in the query route) the query box, the query result display, the saved/old queries bar).

I imagine this would require

• using something like svelte-dnd-action to allow rearranging the layout,
• and using the resize CSS property to allow native element resize.
• I imagine the resize property would exist on containers that would each containe a single "region" that is draggable.
• There should be listeners to resize the container region when a large section is moved to a small region (and swap the small section to the other region).
• There should be listeners to accommodate the resize of a region by resizing other regions.

This would require refactoring the layouts to be compatible with drag and drop.

[mosheduminer]

Another implementation possibility is to use svelte-grid.